* Add core of new union signature logic and test - needs intersection signature logic to fully work
* Add inversion of variance for class props lookup from union sig returns
* Fix lints
* Combine parameter names for nicer quick info
* PR feedback 1
* Fix miscopy
* PR feedback round 2
* Remove argument name combining because loc :(
* Nit cleanup round 3
* Reinline getTupleTypeForArgumentAtPos
* Remove a tad more
* No step on sneky off-by-one error
