Linux: Embed AppImage update information

[shuvashish76]

When trying to update via AppImageUpdate

AppImage having update information would also recognized by other software e.g. AppImageLauncher , AppImageUpdate, AppManager, AM etc...

info:

• https://github.com/AppImageCommunity/AppImageUpdate#update-information-overview
• https://github.com/AppImage/AppImageSpec/blob/master/draft.md#update-information
• https://github.com/ivan-hc/AppImage-tips#how-to-add-delta-updates

Lots of projects already support updating AppImage e.g: LibreWolf, KeePassXC, Sigil etc.

AppImage delta updates which will take less amount of data and time due to downloading only diff.