This is necessary for testing a large number of events (e.g. every key code) within a single build/pass.
The u8_t limitation became apparent during end-to-end testing of #21.
* For now, to be used for FrankenKyria, where both
matrix halves will be attached to the same MCU, but
should be a stepping stone to proper split support
once we have a kscan driver over a split transport.
* Implement multiple instances for mock kscan driver.
innovaker