[MU4] Ported #7022 : Fix #279707: Command line option to update AppImage

[igorkorsukov]

Ported #7022 : Fix #279707: Command line option to update AppImage

@shoogle Could you take a look, is that correct?

[shoogle]

@igorkorsukov, look good so far, but it will also need all these PRs:

• PR [MU3] Partial fix #279707: First steps towards automatic updates on Linux #6919: [MU3] Partial fix #279707: First steps towards automatic updates on Linux
• PR [MU3] Fix AppImage nightly autoupdates and build scripts #6970: [MU3] Fix AppImage nightly autoupdates and build scripts
• PR AppImage: Don't attempt to bundle appimageupdatetool if it's not found #7070: AppImage: Don't attempt to bundle appimageupdatetool if it's not found
• PR [MU3] AppImage: Ensure zsync file is named correctly for stable releases #7380: [MU3] AppImage: Ensure zsync file is named correctly for stable releases

One or two of these might have been partially ported already during a past sync of the CI files between 3.x and master.

Let me know if you'd like me to port these for you. I was planning to but hadn't got round to it yet

[igorkorsukov]

@igorkorsukov, look good so far, but it will also need all these PRs:

• PR [MU3] Partial fix #279707: First steps towards automatic updates on Linux #6919: [MU3] Partial fix #279707: First steps towards automatic updates on Linux
• PR [MU3] Fix AppImage nightly autoupdates and build scripts #6970: [MU3] Fix AppImage nightly autoupdates and build scripts
• PR AppImage: Don't attempt to bundle appimageupdatetool if it's not found #7070: AppImage: Don't attempt to bundle appimageupdatetool if it's not found
• PR [MU3] AppImage: Ensure zsync file is named correctly for stable releases #7380: [MU3] AppImage: Ensure zsync file is named correctly for stable releases

One or two of these might have been partially ported already during a past sync of the CI files between 3.x and master.

Let me know if you'd like me to port these for you. I was planning to but hadn't got round to it yet

Thank you.
It would be great if you could transfer them :)

[shoogle]

@igorkorsukov, I created PR #7582 to port the other changes.