startable without audio

[lyrra]

Enables testing/working without any audio.

• [x] I signed CLA
• [ ] I made sure the code in the PR follows the coding rules
• [ ] I made sure the code compiles on my machine
• [ ] I made sure there are no unnecessary changes in the code
• [ ] I made sure the title of the PR reflects the core meaning of the issue you are solving
• [ ] I made sure the commit message(s) contain a description and answer the question "Why do those changes fix that particular issue?" or "Why are those changes really necessary as improvements?"
• [ ] I made sure the commit message title starts with "fix #424242:" if there is a related issue
• [ ] I created the test (mtest, vtest, script test) to verify the changes I made

[vpereverzev]

If you're interested in testing of app w/o some module, you might be interested in using "stub" classes

[lyrra]

This patch is relevant until both alsa is made unconditionally loaded. And jack is implemented as a second audio output option.

[RomanPudashkin]

The original crash has been fixed, see: https://github.com/musescore/MuseScore/issues/10433#issuecomment-1263330016