feat: install from archive or local directory

[sogladev]

Click "Install addon", see only HTTPS git, and Clone available.

An option in the "Install addon" modal to use a folder and/ or file picker to install a local addon.

• if local folder has a .git/ track it as a git addon

Extra info

Archive formats commonly used are: .zip, .rar, .7z

.addonmanager/ is used to store .git addons. We could add an untracked/ or !manual/ folder to store unpacked archives.

Symlinking feature and subaddon discovery should still be possible. Only updating should be disabled.