Ensure that no action is still queued that may access the mir::input::InputDevice (LP: #1672955)
Shared pointers to mir::input::Device are handed out to other threads and may still be used after the mir::input::InputDevice was removed. To avoid this problem the ActionQueues for manipulating input devices are now per device and will be removed with the InputDevice. Fixes: https://bugs.launchpad.net/bugs/1672955.
Approved by Kevin DuBois, Alan Griffiths, Alexandros Frantzis, mir-ci-bot.