Music App Prefs: Allow disabling priority in launcher, configure vibe strength

[nullstalgia]

Howdy! Happy to rejoin the Pebble family, but in open source this time! It was really fun editing the source of my favorite smartwatch, looking forward to doing more!

I keep Music bound to "Quick Launch: Hold Select", so the prioritization in the Launcher just gets annoying when the app at the top gets shifted without my consent.

Additionally the HAPTIC_FEEDBACK vibe score uses a short 100% pattern, and I felt that was a little aggressive (especially with the repeating vibes from holding Up/Down), so I've added an option to allow changing it with the mobile app's settings page.

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My work is based off of PR #1071, and in which I noticed the desire to bundle these preferences by application. I even attempted to do so within the first commit, consolidating:

  "musicShowVolumeControls",
  "musicShowProgressBar",
  "musicPrioritizeWhenPlaying",
  "musicLongPressVibeIntensity",

into

  "musicAppPreferences",

But, I don't know any Kotlin! (I'm a C and Rust fellow!) So following the flow of something like "hrmPreferences" is non-trivial for me at the moment. I'd be more than happy to help return it to a consolidated struct, but I'd need someone to help me with the Kotlin side of things!

[jplexer]

we gotta be careful here, since the mobile app also needs a corresponding change

[nullstalgia]

I'm aware! And in case my description wasn't super clear, that isn't how the PR is currently laid out, only in the first commit; later I reverted back to the old discrete entries + two new discrete preference keys, like so.

90fe3fa#diff-2604530760c3fbc778755b27d105d89c5633f1621153c1fd6c844bfbbf08305dR112-R115

But to make myself clear once more, I do think the single struct is the preferable method, I simply do not have the requisite Kotlin knowledge to make the correct changes needed in the mobile app. I was hoping I could get some assistance on that side, as I'm far more comfortable with embedded firmware than mobile applications.