Kapi - the new wrapper for capi

[paritytech/capi](https://github.com/paritytech/capi)

PolkadotJS/api is slowly becoming a obsolete thing
and capi would be a go-to lib to interact with (RPC/light) clients

Task is to do fit wrapper (like sub-api) but for capi

ht/ @rphmeier

Start by reviewing paritytech/capi and the repository's existing sub-api wrapper to determine the intended package entry point and exposed surface. Define the wrapper needed for interacting with RPC and light clients, then verify that the resulting package provides the expected capi integration.

Written by the indexing model from the issue text.