tools: switch interactive-evdev to getopt_long

tools: switch interactive-evdev to getopt_long

Requiring long options for this tool means it's immediately obvious what an
invocation does, compare e.g.

  xkbcli interactive-evdev -gcd

to the equivalent:

  xkbcli interactive-evdev --consumed-mode=gtk --enalbe-compose --report-state-changes

This drops the evdev offset argument - that offset should never be anything
other than 8, having this as argument here is more likely to confuse or
produce misleading debugging logs.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>