Port the search results list to GtkListview. Use bindings to set
the title, icon, and subtitle of each row. Remove GcalSearchHitRow
as it's unused now.
For the sake of smooth adaptivity, we need the toolbar buttons
to be constant in both modes instead of moving places from one
mode to another. Instead of duplicating these groups of
buttons, we can refactor them into an object for toolbars
and use them in multiple places.
This commit takes the widgets from the end of the header bar and
creates `GcalToolbarEnd`, which is used in the header bar and the
mobile action bar.
GcalEventPopover gives a preview of the event, and handy access
to the event description and information. It also allows easily
joining meetings if any one if available.
The list of supported meeting URLs is small now, but I hope
more people will contribute as we go.
It is also possible to edit the event through an edit button.