perf: Optimize typedUnion

[FrederikBolding]

Use a constant time lookup for typedUnion instead of .find() as this seems a little faster.

To make this work, I had to modify some of the legacy structs to use our own implementation of literal as otherwise struct.schema.type.type would be literal.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.99%. Comparing base (c1b55b0) to head (48ad9c6).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3275   +/-   ##
=======================================
  Coverage   94.98%   94.99%           
=======================================
  Files         511      511           
  Lines       11313    11328   +15     
  Branches     1741     1747    +6     
=======================================
+ Hits        10746    10761   +15     
  Misses        567      567           

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[FrederikBolding]

@metamaskbot update-pr

[FrederikBolding]

@metamaskbot update-pr