Removed the label property from built-in behaviors, custom behaviors
defined in a few keymaps, and macros generated with ZMK_MACRO().
Now that node names are used to identify behaviors, and names only need
to be unique within the set of behaviors, the names of all behaviors
have been shortened to be similar to their original labels.
This means that any keymaps which reference behavior nodes by name
instead of by label will need to be updated. Keymaps typically use the
labels though, so most keymaps should be unaffected by this change.
* Use lesser-known DT features to skip behaviors not referenced
in the user keymap
* Update the behaviors to skip code if no nodes found.
* Remove some empty config/data structs where unused in
behaviors.
* Add `bt` behavior that can be used to perform certain actions,
such as next/prev identity, reset identity, etc.
NOTE: Multiple identities is only supported for non-split shields,
due to missing Zephyr identity functionality for dual
central/peripheral devices.
* Proper bond reset tied to action, that honors peripheral bonds,
so folks can reset and pair to other hosts, without breaking
bonds between splt halves.
