* Make it easier to test native builds of our shields by adding
`posix_pro_micro` and `posix_seeed_xiao` so you can build posix
target of, e.g. `corne_left` for testing ZMK Studio.
* Use defines to keep either all behaviors with omits, or selective behaviors with
explicit kept behavior, before including `behavior.dtsi` in keymaps.
* Default ZMK_BEHAVIORS_KEEP_ALL when building with the studio RPC
endpoint snippet.
Removed "label" properties which no longer have any function.
Labels are still used as layer names and as identifiers for sending
behaviors between sides of a split keyboard, so those have been left
alone for now.
* Allows removing multilib from docker images
* Run properly in aarch64 host docker
containers for testing on Rasberry Pi.
* Small sticky-keys fix to initialize w/ correct
constant for max uin32_t value.
