Commit.id is not a UUID

`Commit.id` <=> `RepositoryCommit.name`, which is a dashless UUID.

This also implies that `ResourceRef.value.id` is not a UUID.

TODO:
- [ ] Should we drop the UUID validation on all IDs? Ideally our IDs are opaque to users and we are not expressing their shape in the API.

buf/registry/module/v1beta1/branch.proto

@@ -61,10 +61,7 @@ message Branch {
   // TODO: enum?
   bool is_release = 9 [(buf.validate.field).required = true];
   // The id of the latest Commit created on the Branch.
-  string latest_commit_id = 10 [
-    (buf.validate.field).required = true,
-    (buf.validate.field).string.uuid = true
-  ];
+  string latest_commit_id = 10 [(buf.validate.field).required = true];
   // The Digest of the latest Commit pushed to the Branch.
   buf.registry.storage.v1beta1.Digest latest_commit_digest = 11 [(buf.validate.field).required = true];
 }

buf/registry/module/v1beta1/commit.proto

@@ -30,10 +30,7 @@ message Commit {
   option (buf.registry.priv.extension.v1beta1.message).response_only = true;
 
   // The id of the Commit.
-  string id = 1 [
-    (buf.validate.field).required = true,
-    (buf.validate.field).string.uuid = true
-  ];
+  string id = 1 [(buf.validate.field).required = true];
   // The time the Commit was pushed to the BSR.
   //
   // Commits are immutable, so there is no corresponding update_time.

buf/registry/module/v1beta1/resource.proto

@@ -95,7 +95,7 @@ message ResourceRef {
   oneof value {
     option (buf.validate.oneof).required = true;
     // The id of the resource.
-    string id = 1 [(buf.validate.field).string.uuid = true];
+    string id = 1;
     // The fully-qualified name of the resource.
     Name name = 2;
   }

buf/registry/module/v1beta1/tag.proto

@@ -59,10 +59,7 @@ message Tag {
     (buf.validate.field).string.uuid = true
   ];
   // The id of the Commit associated with the Tag.
-  string commit_id = 7 [
-    (buf.validate.field).required = true,
-    (buf.validate.field).string.uuid = true
-  ];
+  string commit_id = 7 [(buf.validate.field).required = true];
   // The Digest of the Commit associated with the Tag.
   buf.registry.storage.v1beta1.Digest commit_digest = 8 [(buf.validate.field).required = true];
   // The id of the User that last updated this Tag on the BSR.

buf/registry/module/v1beta1/tag_service.proto

@@ -105,10 +105,7 @@ message CreateTagsRequest {
       (buf.validate.field).string.max_len = 250
     ];
     // The id of the Commit associated with the Tag.
-    string commit_id = 3 [
-      (buf.validate.field).required = true,
-      (buf.validate.field).string.uuid = true
-    ];
+    string commit_id = 3 [(buf.validate.field).required = true];
   }
   // The Tags to create.
   repeated Value values = 1 [

buf/registry/module/v1beta1/vcs_commit.proto

@@ -65,10 +65,7 @@ message VCSCommit {
     (buf.validate.field).enum.defined_only = true
   ];
   // The id of the Commit associated with the VCSCommit.
-  string commit_id = 8 [
-    (buf.validate.field).required = true,
-    (buf.validate.field).string.uuid = true
-  ];
+  string commit_id = 8 [(buf.validate.field).required = true];
   // The Digest of the Commit associated with the VCSCommit.
   buf.registry.storage.v1beta1.Digest commit_digest = 9 [(buf.validate.field).required = true];
   // The URL of of the repository on the VCS.