Support Notification Channels Specific to Application

(Agile User story-like:)

As a user of Pushover on Android, I need the ability to receive notifications with custom: sounds, priorities, vibrations, and lock screen visibility settings specific to each Pushover "Application" so I can have a better understanding of what notification needs my immediate attention or not.

This can be fairly easily (namely minimal testing needed) implemented into the existing Android app. An Application could have a different Notification Channel for each Application and Pushover Priority level. But these can be created in real-time, in advance, or by user selection.

For example, Google Messages on Android allows a user to go into the notification preferences for a contact, which, at runtime, creates a new Notification Channel that is specific to that contact. Pushover can do the same thing for its Applications, but for all of the respective priorities.

This is a much needed feature and would make Pushover on Android have a more idealistic implementation of notifications, as Google intended and users can make significant use of.