Add Orca and autostart of speech when installing desktop profiles, similar to Debian

[Mudb0y]

describe the request

As someone who's blind and often does reinstalls of my OS, it would be nice to have some desktop accessibility preconfigured when installing with speech, similarly to how Debian does it where Orca starts in the DM, ETC. Ideally I'd also export the common accessibility variables by default, such as QT_ACCESSIBILITY=1 and ENABLE_ACCESSIBILITY=1.