Refactor analysis of collection objects

• Refactor analysis of collection objects in Hercules IR.
  • Move to analysis in hercules_ir/, as will be needed for clone detection.
  • Remove old analysis in hercules_cg/ (mem.rs), which was kind of ugly.
  • Call nodes now may return objects passed in parameters or a new object.

assigned to @rarbore2

mentioned in commit 7b8363fe

merged