Upgrades for: notification_chip.dart

[mattrltrent]

Where it's located: lib > presentation > shared > overlays > notification_chip.dart

Currently, the notification chip appears on the screen when summoned to show some message, but it's got some problems:

• Currently, the little white-line indicating of how long time-wise is left before it leaves the screen isn't always accurate. On bigger and smaller screens it seems to not reach the end properly, or it reaches the end too early.
• Currently, a bunch of notification chips can appear on top of each other if the function is called in quick succession. This looks ugly. Ideally, only 1 would show at once, where if a new notification is triggered, it replaces the one currently being shown.
• Currently, you can't dismiss a notification prematurely - you have to wait for its entire duration to expire before it dismisses itself. This is very annoying. Users should be able to dismiss it themselves with a drag gesture, or perhaps a tap gesture. Its exit animation should be clean too (not just disappearing instantly).

Some places in the app where you can see this notification occur for reference:

• Go to create a post, don't fill out a body or a title, then go to the post details, then click "Submit Confession". This should raise an error notification chip.
• Go to Settings > Contact Confesi, then click the "Copy email address" button. This should raise a success notification chip.