Fix channel headphone toggle LEDs

Add an incoming MIDI -> ALSA control mapping for channel headphone toggle buttons

MIDI LED control

• Load incoming MIDI message -> ALSA control mapping from a file.
• Update this mapping to support all incoming MIDI messages that the NI macOS/Windows driver responds to.
• Update mapping docs to reflect the above.

Note: Control of all other LEDs seems to be handled between the NI drivers and the controller on other platforms, so for the sake of compatibility we'll try to mimic this behavior.

Update docs

Update mappings documentation spreadsheet to reflect bug fixes

Fix deck loop controls

• Fix the deck loop controls so that turning / pressing these rotary encoders sends the correct MIDI message.
• Add some comments about the few remaining controls that don't work (this looks to be the result of a bug with the snd-usb-caiaq kernel module).

All rotary encoders

Add logic to send MIDI messages to control the file browser, channel gain, beat jumps and loop lengths

Gain rotary encoders

• Add logic to send MIDI messages to control gain
• Add debug messages related to snd_usb_caiaq events in traktor-s4-mk1-midify
• Add more packaging info to pyproject.toml

Tidy up packaging

• Updates the package format to use pyproject.toml.
• Enable CLI commands to be run from any directory by using absolute paths for data files by default.

Jog wheels

Add logic to handle jog wheel control in a way that Mixxx expects. #1

Usability improvements:

• Auto detect controller when using traktor-s4-mk1-print-events
• Add CLI options to control jog wheel sensitivity / print debug messages

Complete default input mappings

Add complete mapping for event codes to MIDI, usability improvements:

• Automatically detect controller / ALSA devices at startup
• Load mappings into a more efficient data structure
• Load input mappings from a CSV file, allowing possibility for user supplied mapping files to be supplied via CLI at a later time

LEDs

Get some LEDs working on the controller:

• Add support for sending MIDI messages to the controller from Mixxx
• Add method to handle these messages and shell out to amixer to control LEDs
• Add a method that handles Mixxx's VuMeter messages