[client] recovery: add force keybind

Add a configured escape key plus Shift+R command that requests display
recovery from the LGMP transport and switches video to SPICE.

Track the request on the main thread, report its asynchronous result,
and return its producer instance with the request serial for exact
correlation.

Preserve normal escape+R rotation behavior, including custom Shift
escape keys.

doc/usage.rst

@@ -46,6 +46,8 @@ not have :kbd:`ScrLk`.
      - Toggle the video stream
    * - :kbd:`ScrLk` + :kbd:`R`
      - Rotate clockwise by 90 degrees
+   * - :kbd:`ScrLk` + :kbd:`Shift` + :kbd:`R`
+     - Force guest display recovery mode
    * - :kbd:`ScrLk` + :kbd:`=`
      - Ask the IDD to match the client window resolution
    * - :kbd:`ScrLk` + :kbd:`I`