perf: Use typedUnion for UserInputEventStruct

[FrederikBolding]

Use typedUnion for UserInputEventStruct. This comes with some performance benefits and also makes the error message more readable.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.80%. Comparing base (18e4993) to head (bda523e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3344   +/-   ##
=======================================
  Coverage   97.80%   97.80%           
=======================================
  Files         364      364           
  Lines        9911     9912    +1     
  Branches     1616     1616           
=======================================
+ Hits         9693     9694    +1     
  Misses        218      218           

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