Improvements and fixes for next bus notifications (tracking issue)

[jumpy-cat]

Ideally all bug fixes and small enchancements make it into maizebus 2
Bold = try to get into maizebus 2

Bug Fixes

• determine cause of black screen when update button is spammed (edward)
  • appeares fixed by loading state for button
  • navigator hits an assertion, probably while building the ReminderForm, seems like it gets destroyed while other pieces of code still try to modify it
  • reordering Navigator.pop and the check for context.mounted fixes root cause
• determine cause of weird reminder selectior behavior when duplicates are present (edward)
  • rtidsToChange gets all active reminders added to it whenever the widget is rebuilt, which overrides the removal that happens when unchecking
• when new reminders are added, existing reminders for the same stop+route are removed
  • should allow some simplification of the FE (wasn't really simplified but still needed changes)
• loading state for the setting notifications update button to avoid spamming the backend (ishan)
• hide reminder widgets when showing route on map (in the nav view) (edward)
• make sure it can't softlock (edward)

Small Enhancements

• improve wording of notification messages (add missing space, better minute numbers, less than vs exactly) (edward)
• reminder widgets don't flash when updating (edward)
• reminder widgets show arrival times immediately if possible (edward)
  • fix sort order (edward)
• match the stylesheet (make text smaller to fit normal) (edward)
• different dark mode style for reminder widget (use card style) (edward)
• right shape for ride route icons (reminder widget) (ishan)
• make sure reminder stuff is hidden when no internet banner is showing

Larger Enhancements Stuff the isn't very urgent / is currently blocked.

• collapsable view that also serves as loading / error state
• add route images to the notifications? (needs feasibilty test for placing the image into the app icon)
• full reminder widget with progress bar??
• After Ensure notif reqests get sent #79 is merged the updating process for the notification widget can be streamlined a bit
• remove the broken and unused function isActiveReminder