## Description
This PR removes simple prefix from all types in the crypto/merkle directory.
The two proto types `Proof` & `ProofOp` have been moved to the `proto/crypto/merkle` directory.
proto messge `Proof` was renamed to `ProofOps` and `SimpleProof` message to `Proof`.
Closes: #2755
Migrates the `rpc` package to use new JSON encoder in #4955. Branched off of that PR.
Tests pass, but I haven't done any manual testing beyond that. This should be handled as part of broader 0.34 testing.
The certifier package is renamed to light. This is more descriptive
especially in the wider blockchain context. Moreover we are building
light-clients using the light package.
This also adds godocs to all exported functions.
Furthermore it introduces some extra error handling. I've added one TODO
where I would like someone else's opinion on how to handle the error.