add test for easyconfig file permissions

[Flamefire]

Extracted the test only from #18646 to check the file permissions of EC files on PR.

Test: ECs are readable, owner-writable and non-executable, i.e. at least 0644 without any executable flag.

An example failure I forced to test the test:
AssertionError: CFITSIO-3.34-ictce-5.5.0.eb must be readable (owner, group, other), not executable, at least owner writable, is: 0o100511

[Micket]

Hm, I'd like to see what this looks like when it actually fails once, but i'm not sure how to trigger such a test locally

[Flamefire]

Hm, I'd like to see what this looks like when it actually fails once, but i'm not sure how to trigger such a test locally

I added an example above:
AssertionError: CFITSIO-3.34-ictce-5.5.0.eb must be readable (owner, group, other), not executable, at least owner writable, is: 0o100511

I.e. where 1 file fails all 3 checks. A single failure would then be e.g. AssertionError: CFITSIO-3.34-ictce-5.5.0.eb must be not executable, is: 0o100555

To trigger: GITHUB_EVENT_NAME=pull_request GITHUB_BASE_REF=develop python -m test.easyconfigs.suite -k test_ec_file_permissions after changing some EC file permissions in a commit

[smoors]

did a quick test, seems to work fine (although running a single test did not work for me, i had to run all of them).

[smoors]

lgtm