Implement support for retrieving subsets of storage maps in `GetAccountProof` endpoint

[drahnr]

[bobbinth]

SmtForest won't have support for LargeSmt - these are separate structs. I think what this issue was meant to cover was that we'll need to start using SmtForest to enable ability for users to request specific entries by key from storage maps (the functionality that we removed in the last release). To do this, we'll need to use the SmtForest structure.

I've renamed the issue accordingly.

[bobbinth]

I believe this is closed by #1428. @drahnr, feel free to re-open if not.