TempRValueElimination: re-implement the pass in swift

Beside cleaning up the source code, the motivation for the translation into Swift is to make it easier to improve the pass for some InlineArray specific optimizations (though I'm not sure, yet if we really need those).
Also, the new implementation doesn't contain the optimize-store-into-temp optimization anymore, because this is covered by redundant load elimination.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/CMakeLists.txt

@@ -33,4 +33,5 @@ swift_compiler_sources(Optimizer
   SimplificationPasses.swift
   StackPromotion.swift
   StripObjectHeaders.swift
+  TempRValueElimination.swift
 )