On Screencasting

Hi,
I'm sending this e-mail to hopefully simplify a bit the review process
of this new protocol that I understand is a bit boring.

kwayland: https://phabricator.kde.org/D28882
kwin: https://phabricator.kde.org/D29015
xdg-desktop-portal-kde: https://phabricator.kde.org/D28884

There's 3 parts but it's basically code moving from xdp-kde to kwin
and a kwayland protocol to orchestrate it.

Something we might want to discuss is if it makes sense to put the
kwayland bit into a separate repo as it only interacts with plasma
components and we don't want ABI restrictions.

Other than that it's mostly a code simplification as is. Then we
probably will want to do more work on the kwin side adding support for
streaming windows and optimise the process, but I wouldn't do it at
this stage.

Thoughts?
Aleix