Add max limit for refs or values in requests

[mfridman]

This PR adds max_items to GetOwnersRequest.

I think we should avoid unbounded repeated refs and have sane limits. If a client needs to resolve >250 IDs or names, they can hit the endpoint multiple times.

Although it's not a list endpoint, used 250 for parity.

[bufdev]

If we do this, we should agree on a global max, i.e. all places that take repeated Refs should have the same limit. I'm fine with 250, but let's add this for the whole API.

[bufdev]

Includes but may not be limited to:

buf/registry/owner/v1beta1/owner_service.proto:36:  repeated OwnerRef owner_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/owner/v1beta1/user_service.proto:51:  repeated UserRef user_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/owner/v1beta1/user_service.proto:151:  repeated UserRef user_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/branch_service.proto:44:  repeated BranchRef branch_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/branch_service.proto:54:  repeated ModuleRef module_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/tag_service.proto:48:  repeated TagRef tag_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/tag_service.proto:114:  repeated TagRef tag_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/module_service.proto:54:  repeated ModuleRef module_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/module_service.proto:163:  repeated ModuleRef module_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/vcs_commit_service.proto:39:  repeated VCSCommitRef vcs_commit_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/module/v1beta1/commit_service.proto:81:  repeated ResourceRef resource_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/owner/v1beta1/organization_service.proto:51:  repeated OrganizationRef organization_refs = 1 [(buf.validate.field).repeated.min_items = 1];
buf/registry/owner/v1beta1/organization_service.proto:139:  repeated OrganizationRef organization_refs = 1 [(buf.validate.field).repeated.min_items = 1];

[mfridman]

This isn't a ref, but I presume we want to set an upper limit for these repeated values as well?

[bufdev]

Yea