* config: Fix multi-argument gesture dispatchers parsing
The `dispatcher` gesture handler used to only handle
the first argument to the dispatcher, while some dispatchers
(e.g., `sendshortcut`) want multiple arguments.
This fixes `ConfigManager` to handle all the arguments
provided to the dispatcher gesture handler.
Fixes#11684.
* test/gestures: Add a test for a gesture with a multi-argument dispatcher
* test/gestures: Factor out `waitForWindowCount`
Reduce code duplication in the gestures test.
