Move snap_manageAccounts to a gated permitted method

[GuillaumeRx]

This PR moves the snap_manageAccounts method from a restricted method to a permitted method.

This allows us to couple it with the Keyring endowment. The implementation checks if the snap has the permission to use the Keyring and throws if not.

This also refactors how the message is passed to the snap. The keyring will now be retrieved on the hook implementation and we will only expose a mutated version of handleKeyringSnapMessage where we will bind the origin coming from the RPC engine to the method hook. This ensures we don't manipulate the origin inside the method implementation.

Fixes: #2798

[Mrtenz]

I don't think we can do this without a breaking change. Snaps may still request the permission which will no longer exist, and it also exists in the permission controller state for existing Snaps.

[GuillaumeRx]

I don't think we can do this without a breaking change. Snaps may still request the permission which will no longer exist, and it also exists in the permission controller state for existing Snaps.

@Mrtenz I'm working on a migration on the extension side and a fix in the snap side :) This should probably be a draft.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.57%. Comparing base (45db6e7) to head (3543200).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2869      +/-   ##
==========================================
+ Coverage   94.48%   94.57%   +0.09%     
==========================================
  Files         487      487              
  Lines       10427    10442      +15     
  Branches     1598     1600       +2     
==========================================
+ Hits         9852     9876      +24     
+ Misses        575      566       -9     

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