Convert test runner to Python

[shuds13]

Trying a Python version of the test runner.

Aim is to simplify and make it easier to see where in the script the tests are being run.

• [x] Test working with github Actions
• [x] Check works with codecov
• [x] Check works with extra tests
• [x] Check test vars are read correctly (e.g. TESTSUITE_EXTRA)
• [x] Compare runs old and new scripts inc. which tests run/coverage/num procs
• [x] Check special build code for forces.x
• [x] Check works right on macOS
• [x] Remove old bash test runner
• [x] Is clean function sufficiently safe
• [x] Does color work on both unit and regression tests.

Changes to tests / approach

• [x] Do we really want to default to printing all test output or only on failure?*
• [x] Remove any commas in directives - e.g: # TESTSUITE_NPROCS: 5, 7
• [DEFERRED] Can .coveragerc files be consolidated and omit lists dont include all unit test dirs.
• [DEFERRED] Can conftest.py be consolidated (seems needs to be in current dir but might be alt config).
• [x] Remove some things that are not generally used like PEP option/python version/test strings/name.
• [x] Do we want to keep REG_RUN_LARGEST_TEST_ONLY which is currently the default.
• [x] Some tests were not being run as had no TESTSUITE directives. Setting default (e.g. local and 4 procs).
• [x] Should revisit test_persistent_uniform_gen_decides_stop.py due to intermittent failures.
• [x] test_1d_sampling_with_profile.py takes a very long time for some reason. Reduce num sims/re-visit profiling?
• [DEFERRED] coverage looks like most of tasmanian gen not being tested.

*Example of run where I've turned the "show output" option off - shows stderr when test fails (could show stdout also): https://github.com/Libensemble/libensemble/actions/runs/11229218671/job/31214403085

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.84%. Comparing base (11aee40) to head (60d63df). Report is 10 commits behind head on develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #1437 +/- ## ============================================ + Coverage 78.33% 90.84% +12.50% ============================================ Files 84 76 -8 Lines 7871 7680 -191 Branches 1408 1354 -54 ============================================ + Hits 6166 6977 +811 + Misses 1484 535 -949 + Partials 221 168 -53 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.