This commit introduces an experimental input-method protocol as an exact
copy of the fle describing the unofficial zwp_input_method_v2 from
squeekboard.
It's also supported by wlroots and smithay.
This protocol is the counterpart to text-input-v3. It gives the
compositor a standard way to outsource the handling of the input method.
Signed-off-by: Dorota Czaplejewicz
