Expand and enhance native-multi-image test - #356

Add testing of allocatable coarrays in the main program

Add new HAVE_ALLOC_COARRAY_CLEANUP flag to control auto-deallocation
of allocatable coarrays at scope exit

Add new HAVE_ALLOC_COARRAY_DEALLOC flag to control explicit deallocation
of allocatable coarrays

Factor old CHECK_ALLOC macro into more generic CHECK_VALL macro

Update CI settings accordingly

Add NAG stand-alone support to check for non-conforming vendor extensions,
and fix a few such issues to ensure strict standards conformance.

Add Gfortran stand-alone support, and a Makefile to drive both.

Fix a critical barrier mismatch defect in test_module_coarray and test_save_extern_coarray

Minor cosmetic cleanups

Enable HAVE_COARRAY by default, so that all multi-image features
are enabled by default with HAVE_MULTI_IMAGE.

Also deploy forward-looking HAVE_LOCK and HAVE_NOTIFY knobs that
default to HAVE_COARRAY and control the relevant type.

Adjust CI settings accordingly.

Replace/augment unchecked console output with programmatic checks

Coverage for:
* THIS_IMAGE(TEAM=)
* NUM_IMAGES(TEAM=)
* TEAM_NUMBER(TEAM=)

…ation

Other minor cleanups

Misc cleanups

lfortran#12370 + lfortran#12371 were fixed in lfortran/lfortran#12405,
merged after release 0.64

This is to allow print-native-flags.F90 to live in the app/
directory, without it being slurped in by `fpm run` as a target

…d compilers

This includes fixes to LLVM issues 214080 and 205953

lfortran/lfortran#12538