* Move away from DT_LABEL.
* Move to DEVICE_DT_GET for non-behavior device access.
* Move various drivers to `gpio_spec_dt` and `DT` related macros.
* Remove mcp23017 while at it, since better upstream driver is
available.
Added ZMK_MACRO_DEFAULT_WAIT_MS and ZMK_MACRO_DEFAULT_TAP_MS to set
global defaults for the wait-ms and tap-ms properties of macros.
Also reduced the default timings for macros, since it's been reported
many times that 100 ms is too slow.