Implement #'exwm-buffer-groups-kill-buffer
Invoke '--remove-buffers before listing buffers
Fix exwm-buffer-groups-move
The default behavior of EXWM is to make
buffers containing X windows accessible only from the workspace they were
created in. This is a useful feature, but introduces some level of inconsistency
as this does not apply to normal buffers. exwm-buffer-groups aims to change
this by associating all buffers with a workspace.