[Enhancement] Linux: Embed AppImage update information

[shuvashish76]

Summary
AppImage Delta updates

When trying to update via AppImageUpdate

Motivation
This is a common standard for updating AppImages.
AppImage having update information would also recognized by other software e.g. AppImageLauncher

Updating will take less amount of data and time due downloading only diff.

Proposed Solution
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

[sakethpathike]

All releases will now include the zsync file. The updater seems to have fetched it from the releases; I'll fix the signature stuff soon.

[shuvashish76]

Awesome, the app is also available at AM package manager now I can fetch delta update via AM as well ;D