Don't allow custonname which renames Id to ID

[amaury1093]

Summary

In proto files, don't allow customname which renames Id to ID.

Rationale

In our proto files, we sometimes use gogoproto's customname tag to rename fields, e.g. ClientId to ClientID, to fit what the Go linter recommends. In the generated *.pb.go files, we indeed see fields with ...ID (capitalized).

In #6918, we are adding grpc-gateway, who generates other files *.pb.gw.go. However, grpc-gateway ignores gogoproto's customname tag, and outputs fields with ...Id (PascalCase). See here for an example.

The Go compiler then obviously complains.

Potential solutions

1. Create a PR on grpc-gateway, to make them take into account gogoproto.
2. Add some plugins/hacks in our ./scripts to manually change Id->ID inside grpc-gateway-generated files *.pb.gw.go.
3. Don't allow customname on Id renaming.

#7032 implements 3.

Notes

• Most of the changes happen in ibc proto files.
• You're still free to use ...ID in variable names and elsewhere in the code, so it might create some small inconsistencies in namings.
• We don't remove all customnames (e.g. Ed25519->ED25519, Url->URL are kept). When generating grpc-gateway files, they didn't seem to interfere. For now we only change ID->Id, as these were the ones that made the compiler shout. But there might be some more in the future.

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