RPC implementation for the storage provider

[serg-temchenko]

A proxy mechanism should be implemented for calls to the full-node RPC endpoint through the polka-storage-provider CLI component. Additionally, it should be possible to add unrelated logic to the parachain that is exposed via RPC. Initially, users should have the ability to run an RPC server via the polka-storage-provider command and gracefully stop it. The foundation for this task should be PR #55.

Please add support of versioning for the RPC endpoints (e.g. v1).

Check this and this TODO's.

After reconsideration, it seems more reasonable to include this server run logic in the default section, like here.

[cernicc]

I think it's better if we run the provider on the run command to be more explicit. Because there will also be other commands available