swift234

Implement a function signature cloner and rewriter.

This split the function signature module pass into 2 functin passes.

By doing so,  this allows us to rewrite to using the FSO-optimized
function prior to attempting inlining, but allow us to do a substantial
amount of optimization on the current function before attempting to do
FSO on that function.

And also helps us to move to a model which module pass is NOT used unless
necesary.

I do not see regression nor improvement for on the performance test suite.

functionsignopts.sil and functionsignopt_sroa.sil are modified because the
mangler now takes into account of information in the projection tree.