[xfce4] Add default icon theme, set pmOS wallpaper and add battery icon in top panel
This PR depends on https://github.com/postmarketOS/xfce4-phone/pull/4
Changes explained in the other PR.
TODO:
-
Tag a new version in xfce4-phone
repository once the above PR is closed -
Update the checksums of postmarketos-ui-xfce4