Extensions now must export a class that conforms to a particular
interface both for the actual extension as well as for prefs:
enable()/disable() methods for the former, fillPreferencesWindow()
for the latter.
This is quite similar to the previous method-based entry points,
but it also gives us a more structured way of providing convenience
API in form of base classes.
Do that in form of Extension and ExtensionPreferences classes on
top of a common ExtensionBase base class.
getSettings(), initTranslations() and the gettext wrappers are
now methods of the common base, while openPreferences() moves
to the Extension class.
Based on an original suggestion from Evan Welsh.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2838>
We unified most code paths earlier, but the common code will still
import Main locally if no extension manager was injected before.
Now that the old extensionUtils was split between extension and
preferences, each of those modules can simply import the manager
from its corresponding environment, and then inject it into the
shared module.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2837>
For the time being this mostly means re-exporting functions
from the shared module. However openPrefs() is now only
available to extensions, and we stop exporting both
getCurrentExtension() and setExtensionManager() to either
extensions or prefs.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2837>
