Implement keyforwarding with a new interface in phosh-private protocol

* protocols/phosh-private.xml: Add "keyboard_event" interface and bump
  version protocol version to 5
* src/phosh.c: Implement methods and bump protocol version
* src/phosh.h: Add phosh_private_keyboard_event struct and new methods
* src/keybindings.{c,h}: PhocKeyCombo now publicly accesible
* src/keyboard.c: Allow forwarding of keysyms
* tests/test-phosh.c: Add simple bind/unbind test for keyboard events
* tests/testlib.c: Bump phosh_private version to 5
parent 50dc0175
Pipeline #57860 passed with stages
in 13 minutes and 45 seconds