Changed the GPIO matrix and direct GPIO key scan drivers to do a single
read per port instead of one read per pin. This is much more efficient
for some types of GPIO drivers, such as I2C GPIO expanders.
To accomplish this with minimal overhead, we now sort input pins by port
at driver init. if we iterate through the pins in the sorted order, all
pins on the same port are consecutive, so we only need to read each port
once the first time we see it.
The key scanning drivers are now automatically enabled when a DT node
with the matching "compatible" property is present and enabled, so they
no longer need to be manually set for each board.
Switched the GPIO matrix driver to debouncing using a simple integrator
algorithm. Whenever a key is pressed, we now scan at a rate controlled
by debounce-scan-period-ms (default 1 ms) until all keys are released,
then return to either waiting for an interrupt or polling more slowly.
The timers for key press and release can now be controlled separately,
so debounce-period is deprecated in favor of debounce-press-ms and
debounce-release-ms. Global Kconfig options
ZMK_KSCAN_DEBOUNCE_PRESS_MS and ZMK_KSCAN_DEBOUNCE_RELEASE_MS are also
added to make these easier to set.
Added documentation for debouncing options.
