[gnoclient] Add direct support for specific queries, create readonly client

[leohhhn]

Description

Currently gnoclient only handles the general query case where we have to pass a specific query path to get what we want. We should add separate functions for all query paths to make the package easier to use.

We should also be able to initialize a readonly client without the signer (provider/signer arch).

[thehowl]

The readonly client can also implement simluate features; similar to how they're now being used in gnokey.