[Calendar App] Back action results in 404

[wrdhub]

Doing the back action on the android app results in a 404.

** Test notes **
Test on android device

• Using the back action in the mail app:
  • From calendar, settings, calendar, or search -> goes to the mail view
  • From the mail view -> closes the app
• Using the back action in the calendar app:
  • From settings or search -> goes to the calendar view
  • From the mail view -> closes the app
• In both apps:
  • If navigation column is open -> the slider is closed
  • If dialog is open (such as mail editor or create calendar) -> the editor is closed

[wrdhub]

For this issue, I'm just fixing the 404. But the result is very unsatisfying. Because of how we handle routing, it results in just closing the app from any calendar view. But we have other issues (#7207 #7215 ) that seek to improve that experience.