Add isSnapId utility function

[Mrtenz]

This adds a isSnapId function which accepts any value, and returns a boolean if the input is a valid Snap ID or not.

This is extracted from #2634.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.43%. Comparing base (e5aeb16) to head (888d91b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2808   +/-   ##
=======================================
  Coverage   94.43%   94.43%           
=======================================
  Files         483      483           
  Lines       10300    10302    +2     
  Branches     1566     1566           
=======================================
+ Hits         9727     9729    +2     
  Misses        573      573           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.