Normalize RPC endpoints

[Mirko-von-Leipzig]

Not for this PR, but it feels like we should normalize these endpoints somehow. For example:

• I'm not sure if we are actually using GetAccountStateDelta in the client - @igamigo, could you check?
• I think the current GetAccountDetails endpoint returns the entire account, which would probably not work for large accounts.
• GetAccountProofsRequest is used primarily for FPI, but maybe it can be used for other things as well?

Generally, we should probably list the use case we have for retrieving account data from the node and see if these 3 methods are still the right way to get this data. @polydez - could you create an issue for this?

Originally posted by @bobbinth in #542 (comment)

Looks like we can also remove CheckNullifiers, but not CheckNullifiersByPrefix (origin comment)?

[Mirko-von-Leipzig]

@igamigo could you follow-up on the above re: GetAccountStateDelta

[igamigo]

Sorry, I think I hadn't responded to that comment because of this discussion that was also going on. In short, we do not currently use the GetAccountStateDelta endpoint (but maybe we should as I mention in the linked comment)