Rearrangements to incidence info drawer and general drawer fixes on mobile

This MR contains a new bottom incidence info drawer arrangement on mobile for better reachability:

simplescreenrecorder-2021-08-30_01.33.43

There are also a multitude of changes and fixes to the todo view's completed todos drawer, which is now a sheet and works correctly. Concretely:

• No more phantom todos on collection change
• The incidence info drawer now opens correctly on selecting a todo
• The context menu now appears correctly on right-click/long press of a todo

Additionally:

• Clicking on a navigation element in mobile mode (i.e. the 'view all todos' button) closes the drawer after the page has changed
• Busy indicator no longer shows up in incidence info drawer when location is given as link