x11/libxkbcommon: expose evdev(4) support in xkbcli

$ sudo xkbcli interactive-evdev
keysyms [ h ] unicode [ h ] layout [ English (US) (0) ] level [ 0 ] mods [ ] leds [ ]
keysyms [ i ] unicode [ i ] layout [ English (US) (0) ] level [ 0 ] mods [ ] leds [ ]

PR: 254583
Approved by: manu
Differential Revision: https://reviews.freebsd.org/D29664