Until now, it didn't matter whether an extension was installed in the
user's home or system-wide. However with support for uninstallation,
there is now a significant different, as that action is only available
for user extensions.
Account for that by separating extensions by type, so that users don't
have to second-guess which extensions can be fully-managed and which
appear as part of the system.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1968
Extensions can have a major impact on stability and performance. Now that
the tool will become the main way for users to manage their extensions, it
is an appropriate place to warn the user of that risk.
Add a small info popover to the headerbar to display that warning, together
with the previously removed hint of where to go for finding new extensions.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1968
Currently when the extensions list is scrolled, it is possible to
keynav out of view, as the scrolling doesn't follow the key focus.
Hook up the adjustment to fix that.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1968
