Controller: Refactoring version handling
In preparation for creating a Beta page (shown on upgrade to a Beta release), this commit changes how the version handling works.
plasmaVersion
, plasmaVersionSplit
and simplePlasmaVersion
are removed in favour of shownVersion
, patchVersion
and releaseUrl
(rather than working it out in QML).
Changes are also made so the shown version is a friendly string matching what we show in the desktop preview banner, and releaseUrl shows an appropriate URL for the current release.