Issue#10611 record broadcast libsamplerate

[ronso0]

I collected some fixes.

First commits are small and self-explanatory, but for the last chunk I ran out of time and commited as a whole.
See commit message for details.

I didn't yet touch the m_oldRecSampleRate which is (I guess) not updated correctly and therefor giving me the UX issue I mentioned earlier.

[ar-in0]

Sorry for the late response - took a break from Mixxx for a few weeks. I just built this PR.

GUI in this PR (above) needs to be fixed.

The above GUI is the target (current state of mixxxdj#15081)

It appears the changes in this PR have undone some of the functionality (and previous fixes). oldrecsamplerate is not being updated correctly. This UX issue was resolved in 7bf99be, before the set of commits in this PR.

• Have you been able to test Issue#10611: Support for custom output samplerates during recording (broadcast pending) mixxxdj/mixxx#15081?

[ronso0]

Oh, sorry for letting this sit so long!

I'm not into this anymore unfortunately.
I rebased and removed the complex refactoring, should now only be some cleanup and a tweak.
Please test.

---

However, there are still a few things that are either wrong, for example setting a fixed width on translatable buttons

    RadioButtonUseCustomSampleRate->setMaximumWidth(80);
    RadioButtonUseDefaultSampleRate->setMaximumWidth(234);

or can be improved

• use mixxx::audio::SampleRate
• remove excessive logging in preferences
• catch [App],samplerate changes and update preferences accordingly
• use helper to set text on RadioButtonUseDefaultSampleRate

Do you think you can take a look, or shall I? Won't happen soon, though.