[Feature Request]: Version the JSON RPC API

[cmwaters]

Implementation ideas

This issue proposes adding a versioning system to the JSON RPC API that would allow us to slowly deprecate older API methods (adding is trivial) so as to give users apt time to migrate to the newer API methods. Ideally this introduction itself is done in a backwards compatible change (i.e. no version specified is interpreted as v1).

How versioning is done (in the url vs in the method vs in the params) is left to be decided.

[Wondertan]

The API reports version at node.Info endpoint: https://github.com/celestiaorg/celestia-node/blob/main/nodebuilder%2Fnode%2Fadmin.go#L29-L34

[cmwaters]

So how would having a v2 while supporting a v1 work?

I think it's common for the client to provide the version that they are currently on and the server tries to match it - that way we can provide some degree of backwards compatibility

[rootulp]

Notes from call:

• Once API is stable, the APIVersion returned can stop being the binary's SemVer version and instead be a distinct stable API version.
• Server can interpret the lack of a client-supplied version in a request as "v0".