crypto/merkle: remove simple prefix (#4989)

## 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

light/rpc/proof.go

@@ -7,8 +7,8 @@ import (
 func defaultProofRuntime() *merkle.ProofRuntime {
 	prt := merkle.NewProofRuntime()
 	prt.RegisterOpDecoder(
-		merkle.ProofOpSimpleValue,
-		merkle.SimpleValueOpDecoder,
+		merkle.ProofOpValue,
+		merkle.ValueOpDecoder,
 	)
 	return prt
 }