[api-minor] Convert getPermissions to return data in a Set

[Snuffleupagus]

This allows the viewer to check for enabled/disabled permissions using Set.prototype.has(), which is generally more efficient than Array.prototype.includes().

Note: Permissions are not enabled by default in the viewer.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.05%. Comparing base (022e958) to head (f250d69).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21738      +/-   ##
==========================================
- Coverage   90.05%   90.05%   -0.01%     
==========================================
  Files         264      264              
  Lines       67094    67093       -1     
==========================================
- Hits        60422    60420       -2     
- Misses       6672     6673       +1     

Flag	Coverage Δ
browsertest	66.30% <0.00%> (+<0.01%)	⬆️
fonttest	9.03% <ø> (ø)
integrationtest	69.34% <100.00%> (-0.01%)	⬇️
unittest	58.35% <75.00%> (+0.01%)	⬆️
unittestcli	56.70% <75.00%> (-0.02%)	⬇️

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[timvandermeij]

Thanks!