[Suggestion] Trying to revive the functionality of `extras/Lockscreen.qml`

[Olf0]

extras/Lockscreen.qml was identified as historic, unused code (a few more details in the last paragraph here).

The obvious solution IMO is to transform extras/Lockscreen.qml into a Patch for Patchmanager.

Notes

• Most paths have to be adapted, e.g. the cache location was moved meanwhile due to the adaptations for SailJail (see PRs [Feature] Add local cover art when importing tracks #75, Change the organisation name #51 etc.).
• It is full or references to mpris, among them problematic ones as import org.coderus.mpris 2.0 as Mpris2. Mpris aspects ought to be reworked anyway, see issue [Suggestion] Use Amber.Mpris instead of org.nemomobile.mpris on newer SailfishOS releases #98.

P.S.: Aside of technical aspects this file also looks problematic under copyright / licensing aspects. This is what Patchmanager for SailfishOS (and its original foundation: AUSMT for WebOS) was invented for: to alter proprietary script files.