
Now that we allow extensions at the lock screens, extensions are allowed for every session mode gnome-shell would typically change to at runtime. This means there's little advantage to having an allowExtensions property in the session mode definition. This commit simplifies the code a bit by dropping the property. Third party session modes can still lock down extensions through gsettings if they need to. Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1967>