Standardize how CLI commands and REST + socket endpoints are registered

[faboweb]

Currently registering REST endpoints and CLI commands is highly individual. A developer would create a REST hanler and a CLI handler that parse their own data and apply them to some logic. This produces a lot of duplicate code.
We discussed, that it would make sense to to have one standardized way/method to register endpoints. This method would in one go register REST, CLI and sockets.

But we also said, that this would again be a big refactor and we will probably be doing this after launch.

Pulling in @rigelrozanski @mappum @jaekwon @gamarin2

[jackzampolin]

We have, since this issue was opened, standardized the endpoints a bit on our modules. We have also moved to using queriers to standardize database queries and used those functions to feed both the lite-client and the gaiacli. I think we can close this issue in favor of #1081 (the remaining work here)

[faboweb]

I was speaking more of something like have one function: RegisterCmd('GET' 'keys', handler) that would setup a cli cmd gaiacli keys that outputs data and sets up a REST route GET /keys that returns data. This would make working with the SDK as an SDK a lot easier I guess.

#post-launch

[jackzampolin]

@faboweb we already have that I think... Please open another issue with details there if you could

[faboweb]

@cwgoes can you confirm?