Move DND access request to a similar dialog

Yields a small performance improvement

receiver doesn't need disk IO

 - Don't name the custom edittext the same as the original one
 - Add hints to text fields
 - Set importantForAutofill to no for text fields
 - Explicitly enable backup of app data
 - Please stop generating warnings for my inkscape svg lol

 - Minor performance improvement from not needing a file lock
 - Do not assume MainActivity will not be instantiated twice, obviously it will
 - Do not attempt to create the schedules file if it does not exist
   This will result in an empty file and cause an error on next read

Hopefully there aren't any bugs left