- Add ZMK_KSCAN_MATRIX_POLLING config flag to Kconfig
- Update matrix driver code to use the above flag to conditionally add the handling code for polling operations.
* Basic Clueboard Californai Macropad shield definition.
* New "direct" KSCAN driver that supports non-matrix direct
wiring for switches, needed for macropad that doesn't have
a matrix at all.
* Some renames for existing KSCAN GPIO driver to make the implied
"matrix" part explicit.