Add Snap RPC wrappers

[FrederikBolding]

Add wrapper functions to the SDK for most of the RPC methods supported by snap.request.

Fixes https://github.com/MetaMask/snaps/issues/2338

[FrederikBolding]

@metamaskbot update-pr

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.41%. Comparing base (8ab64ec) to head (b0282a2). Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2332      +/-   ##
==========================================
+ Coverage   94.38%   94.41%   +0.02%     
==========================================
  Files         441      442       +1     
  Lines        9106     9148      +42     
  Branches     1405     1411       +6     
==========================================
+ Hits         8595     8637      +42     
  Misses        511      511              

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[FrederikBolding]

@metamaskbot update-pr