[flang] Check module subprogram against separate module procedure

When a module subprogram has the MODULE prefix the following must match
with the corresponding separate module procedure interface body:
- C1549: characteristics and dummy argument names
- C1550: binding label
- C1551: NON_RECURSIVE prefix

SubprogramMatchHelper performs all of these checks.

Rename separate-module-procs.f90 to separate-mp01.f90 so we can have
separate-mp02.f90 (etc).

Make ShapesAreCompatible public in characteristics.h.

Add Scope::IsSubmodule.

Original-commit: flang-compiler/f18@d121578af17109de3cea23617e4b8239971b5527
Reviewed-on: https://github.com/flang-compiler/f18/pull/1080