fix: Consider protocol Snaps when determining isSupportedScope

[FrederikBolding]

As per request from the wallet API team and after discussion with them we want to consider protocol Snaps when determining the return value of isSupportedScope. Previously we assumed that a scope was not serviceable if no accounts existed, but that isn't entirely accurate enough.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.87%. Comparing base (8bfaf95) to head (c73ab11).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3284   +/-   ##
=======================================
  Coverage   94.87%   94.87%           
=======================================
  Files         517      517           
  Lines       11335    11336    +1     
  Branches     1749     1750    +1     
=======================================
+ Hits        10754    10755    +1     
  Misses        581      581           

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