remove fauxMatch for tyFromExpr, remove tyProxy and tyUnknown aliases

[metagn]

updated version of #22193

After #22029 and the followups #23983 and #24005 which fixed issues with it, tyFromExpr no longer match any proc params in generic type bodies but delay all non-matching calls until the type is instantiated. Previously the mechanism fauxMatch was used to pretend that any failing match against tyFromExpr actually matched, but prevented the instantiation of the type until later.

Since this mechanism is not needed anymore for tyFromExpr, it is now only used for tyError to prevent cascading errors and changed to a bool field for simplicity. A change in semtypes was also needed to prevent calling fitNode on default param values resolving to type tyFromExpr in generic procs for params with non-generic types, as this would try to coerce the expression into a concrete type when it can't be instantiated yet.

The aliases tyProxy and tyUnknown for tyError and tyFromExpr are also removed for uniformity.

[github-actions]

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