Re-write Predication to use FunctionEditor

• Write new Predication pass using FunctionEditor
  • Uses less analysis info, can work on branches outside fork-joins.
  • Supports partial predication (when some strict subset of inputs to a region form a simple branch, the corresponding strict subset of inputs to phis on the region are predicated).
• New WritePredication pass for converting a branch over writes to a branch over data and indices inputs to a single write, reducing need for spilling in GCM.

requested review from @aaronjc4

assigned to @rarbore2

added 1 commit

• 8e7bc490 - Fix WritePredication

Compare with previous version

merged

mentioned in commit a4ac43fb