chore: shorten variable name that is quite clear from context

`pubkeyRegistrationParams` => `params`
see discussion here:
#100 (comment)

src/BLSApkRegistry.sol

@@ -96,13 +96,13 @@ contract BLSApkRegistry is BLSApkRegistryStorage {
     /**
      * @notice Called by the RegistryCoordinator register an operator as the owner of a BLS public key.
      * @param operator is the operator for whom the key is being registered
-     * @param pubkeyRegistrationParams contains the G1 & G2 public keys of the operator, and a signature proving their ownership
+     * @param params contains the G1 & G2 public keys of the operator, and a signature proving their ownership
      */
     function registerBLSPublicKey(
         address operator,
-        PubkeyRegistrationParams calldata pubkeyRegistrationParams
+        PubkeyRegistrationParams calldata params
     ) external onlyRegistryCoordinator returns (bytes32 operatorId) {
-        bytes32 pubkeyHash = BN254.hashG1Point(pubkeyRegistrationParams.pubkeyG1);
+        bytes32 pubkeyHash = BN254.hashG1Point(params.pubkeyG1);
         require(
             pubkeyHash != ZERO_PK_HASH, "BLSApkRegistry.registerBLSPublicKey: cannot register zero pubkey"
         );
@@ -120,29 +120,29 @@ contract BLSApkRegistry is BLSApkRegistryStorage {
 
         // gamma = h(sigma, P, P', H(m))
         uint256 gamma = uint256(keccak256(abi.encodePacked(
-            pubkeyRegistrationParams.pubkeyRegistrationSignature.X, 
-            pubkeyRegistrationParams.pubkeyRegistrationSignature.Y, 
-            pubkeyRegistrationParams.pubkeyG1.X, 
-            pubkeyRegistrationParams.pubkeyG1.Y, 
-            pubkeyRegistrationParams.pubkeyG2.X, 
-            pubkeyRegistrationParams.pubkeyG2.Y, 
+            params.pubkeyRegistrationSignature.X, 
+            params.pubkeyRegistrationSignature.Y, 
+            params.pubkeyG1.X, 
+            params.pubkeyG1.Y, 
+            params.pubkeyG2.X, 
+            params.pubkeyG2.Y, 
             messageHash.X, 
             messageHash.Y
         ))) % BN254.FR_MODULUS;
 
         // e(sigma + P * gamma, [-1]_2) = e(H(m) + [1]_1 * gamma, P') 
         require(BN254.pairing(
-            pubkeyRegistrationParams.pubkeyRegistrationSignature.plus(pubkeyRegistrationParams.pubkeyG1.scalar_mul(gamma)),
+            params.pubkeyRegistrationSignature.plus(params.pubkeyG1.scalar_mul(gamma)),
             BN254.negGeneratorG2(),
             messageHash.plus(BN254.generatorG1().scalar_mul(gamma)),
-            pubkeyRegistrationParams.pubkeyG2
+            params.pubkeyG2
         ), "BLSApkRegistry.registerBLSPublicKey: either the G1 signature is wrong, or G1 and G2 private key do not match");
 
-        operatorToPubkey[operator] = pubkeyRegistrationParams.pubkeyG1;
+        operatorToPubkey[operator] = params.pubkeyG1;
         operatorToPubkeyHash[operator] = pubkeyHash;
         pubkeyHashToOperator[pubkeyHash] = operator;
 
-        emit NewPubkeyRegistration(operator, pubkeyRegistrationParams.pubkeyG1, pubkeyRegistrationParams.pubkeyG2);
+        emit NewPubkeyRegistration(operator, params.pubkeyG1, params.pubkeyG2);
         return pubkeyHash;
     }
 

src/RegistryCoordinator.sol

@@ -147,21 +147,21 @@ contract RegistryCoordinator is EIP712, Initializable, IRegistryCoordinator, ISo
      * @notice Registers msg.sender as an operator for one or more quorums. If any quorum reaches its maximum
      * operator capacity, this method will fail.
      * @param quorumNumbers is an ordered byte array containing the quorum numbers being registered for
-     * @param pubkeyRegistrationParams contains the G1 & G2 public keys of the operator, and a signature proving their ownership
-     * @dev the `pubkeyRegistrationParams` input param is ignored if the caller has previously registered a public key
+     * @param params contains the G1 & G2 public keys of the operator, and a signature proving their ownership
+     * @dev the `params` input param is ignored if the caller has previously registered a public key
      */
     function registerOperator(
         bytes calldata quorumNumbers,
         string calldata socket,
-        IBLSApkRegistry.PubkeyRegistrationParams calldata pubkeyRegistrationParams
+        IBLSApkRegistry.PubkeyRegistrationParams calldata params
     ) external onlyWhenNotPaused(PAUSED_REGISTER_OPERATOR) {
         /**
          * IF the operator has never registered a pubkey before, THEN register their pubkey
-         * OTHERWISE, simply ignore the provided `pubkeyRegistrationParams`
+         * OTHERWISE, simply ignore the provided `params`
          */
         bytes32 operatorId = blsApkRegistry.getOperatorId(msg.sender);
         if (operatorId == 0) {
-            operatorId = blsApkRegistry.registerBLSPublicKey(msg.sender, pubkeyRegistrationParams);
+            operatorId = blsApkRegistry.registerBLSPublicKey(msg.sender, params);
         }
 
         // Register the operator in each of the registry contracts
@@ -192,16 +192,16 @@ contract RegistryCoordinator is EIP712, Initializable, IRegistryCoordinator, ISo
      * @notice Registers msg.sender as an operator for one or more quorums. If any quorum reaches its maximum operator
      * capacity, `operatorKickParams` is used to replace an old operator with the new one.
      * @param quorumNumbers is an ordered byte array containing the quorum numbers being registered for
-     * @param pubkeyRegistrationParams contains the G1 & G2 public keys of the operator, and a signature proving their ownership
+     * @param params contains the G1 & G2 public keys of the operator, and a signature proving their ownership
      * @param operatorKickParams are used to determine which operator is removed to maintain quorum capacity as the
      * operator registers for quorums.
      * @param churnApproverSignature is the signature of the churnApprover on the operator kick params
-     * @dev the `pubkeyRegistrationParams` input param is ignored if the caller has previously registered a public key
+     * @dev the `params` input param is ignored if the caller has previously registered a public key
      */
     function registerOperatorWithChurn(
         bytes calldata quorumNumbers, 
         string calldata socket,
-        IBLSApkRegistry.PubkeyRegistrationParams calldata pubkeyRegistrationParams,
+        IBLSApkRegistry.PubkeyRegistrationParams calldata params,
         OperatorKickParam[] calldata operatorKickParams,
         SignatureWithSaltAndExpiry memory churnApproverSignature
     ) external onlyWhenNotPaused(PAUSED_REGISTER_OPERATOR) {
@@ -213,7 +213,7 @@ contract RegistryCoordinator is EIP712, Initializable, IRegistryCoordinator, ISo
          */
         bytes32 operatorId = blsApkRegistry.getOperatorId(msg.sender);
         if (operatorId == 0) {
-            operatorId = blsApkRegistry.registerBLSPublicKey(msg.sender, pubkeyRegistrationParams);
+            operatorId = blsApkRegistry.registerBLSPublicKey(msg.sender, params);
         }
 
         // Verify the churn approver's signature for the registering operator and kick params

src/interfaces/IBLSApkRegistry.sol

@@ -98,11 +98,11 @@ interface IBLSApkRegistry is IRegistry {
     /**
      * @notice Called by the RegistryCoordinator register an operator as the owner of a BLS public key.
      * @param operator is the operator for whom the key is being registered
-     * @param pubkeyRegistrationParams contains the G1 & G2 public keys of the operator, and a signature proving their ownership
+     * @param params contains the G1 & G2 public keys of the operator, and a signature proving their ownership
      */
     function registerBLSPublicKey(
         address operator,
-        PubkeyRegistrationParams calldata pubkeyRegistrationParams
+        PubkeyRegistrationParams calldata params
     ) external returns (bytes32 operatorId);
 
     /**