This fixes a crash that happens when input_method_new or text_method_new events are emitted after the seat has been freed.
This ports swaywm/wlroots#1203, swaywm/wlroots#1303, swaywm/wlroots#1308, swaywm/wlroots#1759 rootston part to sway. Co-Authored-By: Leo Chen <leo881003@gmail.com>