gRPC and appmodulev2 handlers

[julienrbrt]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

Handlers do not register grpc service.
Additionally, the grpc server doesn't create grpc service for handler either.

This first point gives a problem to AutoCLI which checks the interface registry for creating commands.
The second point gives issues to any customer requiring gRPC for queries.

We should somehow add support for gRPC for handlers (in runtime and/or grpc server).

Cosmos SDK Version

v2

How to reproduce?

Try to enable AutoCLI when using handlers instead of msg/query server: https://github.com/cosmos/cosmos-sdk/actions/runs/10813674735/job/29998285552

[julienrbrt]

With the new gRPC v2 service, this is solved.
We should still check about AutoCLI in another issue

[julienrbrt]

ref: #22333