Show Extensions Preferences App when installing an extension
Right now when one installs an extension from extensions.gnome.org all that happens is: you hit the switch on that site and you get the dialog about installing the extension, but no other user-facing things occur–it is not obvious where you go to a) manage the extension settings, b) remove/disable the extension, or C) see a list of all extensions to which this extension is ostensibly being added.
We should probably show the Extensions app either after the installation of an extension is completed or during so it is more obvious what is happening when you press install on an extension.