Feature/general indices gatscat

[abrooks1085]

Description
Add support for mpp_pelist_scatter and mpp_pelist_gather with generalized indices (dim_order), including correct handling of non-canonical storage layouts, along with a corresponding unit test.

This change ensures that scatter and gather operations work correctly when array data is stored in a layout that does not follow the canonical (i, j, k) ordering. Data movement remains consistent across MPI ranks regardless of how dimensions are permuted in memory.

A new test (test_mpp_pelist_gatscat_gen_ind) is introduced to validate pelist scatter/gather behavior across multiple permutations of storage layout.

How Has This Been Tested?
amdbox + intel + Autotools

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes

[J-Lentz]

The new test seems to fail on C5 with ifx 2025.2.1. I have the following flags enabled: -traceback -debug -check all

Image              PC                Routine            Line        Source             
libFMS.so.27.0.0   00007FF7FF6E63C0  mpp_gather_int4_1          48  mpp_gather.fh
libFMS.so.27.0.0   00007FF7FF702022  mpp_gather_pelist         216  mpp_gather.fh
lt-test_mpp_pelis  00000000004114B1  test_gather               283  test_mpp_pelist_gatscat_gen_ind.F90
lt-test_mpp_pelis  000000000040D74F  test_mpp_pelist_g          62  test_mpp_pelist_gatscat_gen_ind.F90
lt-test_mpp_pelis  000000000040D12D  Unknown               Unknown  Unknown
libc.so.6          00007FF7FE62BE6C  Unknown               Unknown  Unknown
libc.so.6          00007FF7FE62BF35  __libc_start_main     Unknown  Unknown
lt-test_mpp_pelis  000000000040D031  Unknown               Unknown  Unknown
forrtl: severe (408): fort: (7): Attempt to use pointer RBUF when it is not associated with a target