[Suggestion] Add command line option to integrate AppImages

[Trainmaster2]

I just installed Gear Lever after hearing about it, and I already like it more than AppImageLauncher. However, I did notice one feature that AppImageLauncher has that Gear Lever doesn't: the ability to integrate AppImages from the command line. AppImageLauncher provides an ail-cli integrate command to allow this. All I'd really like is some way for an unattended install script to integrate AppImages.