[flang] Improve error message for procedure passed as invalid argument to an intrinsic

Support forward references to sibling module procedures

Add tests, handle corner cases

Rename new test

Original-commit: flang-compiler/f18@234bb519cd38d0b9234fc0b4a8d11cfcb9935e6a
Reviewed-on: https://github.com/flang-compiler/f18/pull/1076