Better API for getting a contract instance after deploying it

[spalladino]

Deploying a contract using one of the ts wrappers produces redundant code, since the user needs to use a static method of the contract class to create the deployment, and then manually create an instance of that same class. The deployment should just return a Contract instance.

const contract = await ZkTokenContract.deploy(aztecRpcServer, 100n, owner)
      .send()
      .wait()
      .then(r => new ZkTokenContract(r.contractAddress!, wallet)); // Should not be necessary to refer to ZkTokenContract again!

Same goes when using the ContractDeployer:

const deployer = new ContractDeployer(abi, aztecRpcServer);
const tx = deployer.deploy().send();
await tx.isMined(0, 0.1);
const receipt = await tx.getReceipt();
const contract = new Contract(receipt.contractAddress!, abi, wallet); // Should not be necessary to create an instance manually using the same `abi`!