Fix browser notification permission request logic

[ClearlyClaire]

Issue

Up until now, the notification permission was requested by Mastodon after a random amount of time within the first 2 minutes of running it, which, in addition to being unpleasant and not very predictable, does not work on Firefox anymore, because it now requires the request to be a result of user interaction.

Proposed changes

• Add some code to track the state of the permission (since it can be changed at any moment by the user)
  Note: this does not always work, as for some reason, Firefox does not report “prompt” states and report them as “granted” instead (with no change event between the two)
• Request permission whenever the user manually turns on a alert setting that was off (partially done, error message missing when the permission is denied)
  
  
• Add a red badge to the notification column's settings button whenever the permissions aren't sufficient to honor the selected settings
  
  
• Add the same red badge on the notification icon in navigation panels/tabs when the notification column isn't mounted
• Request notification permission at the end of the tutorial, and set the settings according to the response, instead of requesting permissions within two minutes of runtime
  

Other things to investigate

• Does the push notifications have the same issues?

[ClearlyClaire]

Implemented everything I planned to. However, I have not checked whether push notifications are currently properly handled, but I can do that in the future if the approach proposed here is accepted.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ClearlyClaire]

Ping @Gargron

[ClearlyClaire]

Rebased on master.