[tests] Add tests for skip/enable-plugins merge from config and cmdline

[jcastill]

Verify that skip-plugins and enable-plugins are merged (not replaced)
when specified in both sos.conf and command line.

This is a regression test for commit 8fc655a, which fixed the merge
behavior. The new tests verify both effective options
logging in sos.log and actual plugin execution.

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[jcastill]

Some quick notes and questions:

• I based the *_sos.conf files on the one we have for report_tests/option_tests, but I can clean them up by removing the commented options and leaving just what's needed for the tests.
• I have my doubts about the test location. I have them live inside option_tests because of the cmdline options, but then I decided to move them to a specific new location inside plugins. Does this location make sense?
• Any improvements regarding test names are welcome, as always :)
• Considered adding a test for preset vs config file vs cmdline, to make it more complete. Thoughts on this?

[packit-as-a-service]

Congratulations! One of the builds has completed. 🍾

You can install the built RPMs by following these steps:

• sudo dnf install -y 'dnf*-command(copr)'
• dnf copr enable packit/sosreport-sos-4358
• And now you can install the packages.

Please note that the RPMs should be used only in a testing environment.

[arif-ali]

• I based the *_sos.conf files on the one we have for report_tests/option_tests, but I can clean them up by removing the commented options and leaving just what's needed for the tests.

I agree, let's clean up the comments, at least that's my opinion

• I have my doubts about the test location. I have them live inside option_tests because of the cmdline options, but then I decided to move them to a specific new location inside plugins. Does this location make sense?

I don't have an opinion on that, as long as we're testing

• Any improvements regarding test names are welcome, as always :)

Naming is cool with me

• Considered adding a test for preset vs config file vs cmdline, to make it more complete. Thoughts on this?

I think that would make sense, then it covers all the options

[jcastill]

I've added some extra tests to cover more use cases