[flang] Refine "same type" testing for intrinsic arguments (#125133)
Some errors aren't being caught, such as the case in the linked bug
where the PAD= argument to RESHAPE() didn't have the same declared type
as the ARRAY=; this led to a crash in lowering. Refine the "same type"
testing logic for intrinsic procedures, and add a better test.
Fixes https://github.com/llvm/llvm-project/issues/124976.