grass.script: Scan GRASS_ADDON_BASE in get_commands()

[saket0187]

This PR addresses issue mentioned in #3885

I have tested and verified that the output now includes installed extensions in the returned set.

[wenzeslaus]

This looks good, but the user's expectation would probably be also looking at GRASS_ADDON_PATH here.

https://grass.osgeo.org/grass-devel/manuals/variables.html

[wenzeslaus]

Given this is based on a feature request, there is no test coverage. There are some g.extension tests where you can add this as an additional step conforming that GRASS_ADDON_BASE actually works. For GRASS_ADDON_PATH, it seems like the best solution is to create pytest-based test and create couple scripts in different dirs.

[saket0187]

I have added a few lines to scripts/g.extension/tests/g_extension_test.py. Since conftest.py already configures GRASS_ADDON_BASE, I thought using that setup would be enough. I have also added a test in python/grass/script/tests/grass_script_core_get_commands_test.py that creates dummy executables to confirm get_commands() correctly scans the paths specified in GRASS_ADDON_PATH.

Do let me know if anything is incorrect or if any changes are needed.

@wenzeslaus The Windows 2022 build is failing due to HTTP 404 errors, which appears unrelated to my changes; my local tests are passing successfully.

[wenzeslaus]

The pytest has a single test, no? Rework it to yield session instead of tools.

[saket0187]

Currently there's only one test file right now (excluding conftest.py), But I have simplified the fixture to yield session directly which is good to have if we add some tests later. I moved the Tools logic into the test itself; shouldn't make much difference performance-wise since it's just used once.

[wenzeslaus]

This looks great now. Thank you.

We should merge only after the Windows CI is back since this actually needs the Windows check.