refactor(split): Refactor split code for extension
Extract central/peripheral code to allow for plugging in alternate
transports, instead of tying all split logic to BT.
feat(split): Add full-duplex wired split support
* Depends on full-duplex hardware UART for communication.
* Supports all existing central commands/peripheral events, including
sensors/inputs from peripherals.
* Only one wired split peripheral supported (for now)
* Relies on chosen `zmk,split-uart` referencing the UART device.
docs: Add wired split config docs.
Migrate split to its own dedicated config file, and add details
on wired split config.
Co-authored-by: Nicolas Munnich <98408764+Nick-Munnich@users.noreply.github.com>
fix: Properly override stack size on RP2040
Move the system work queue stack size override on RP2040 ouf of
a `ZMK_BLE` conditional so it is properly applied generally for that
SoC.
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Co-authored-by: Nicolas Munnich <98408764+Nick-Munnich@users.noreply.github.com>
