[Accessibility] Need to be able to sythesize mouse events

[Piñeiro]

GNOME Assistive Technologies need to be able to synthesize mouse events. 
Use cases:
* Perform a mouse button click for users who cannot use a physical mouse
* Route the mouse pointer to an object or element to trigger its hover 
action

The Orca screen reader currently provides these commands via calls to 
AT-SPI2's atspi_generate_mouse_event() which in turn calls 
spi_dec_x11_generate_mouse_event() [1]. The equivalent functionality is 
needed for Wayland environments.

How are we going to accomplish this?

[1] 
https://git.gnome.org/browse/at-spi2-core/tree/registryd/deviceeventcontroller-x11.c#n1404

-- 
Alejandro Piñeiro Iglesias (apinheiro at igalia.com)