Filter Dismissed Notifications in Dropdown

[gmeben]

After marking notifications as read within the notifications dropdown in the upper right of the navigational header, those read notifications still appear. This means unread notifications could be blocked from being viewed in this dropdown after other notifications are read.

Filter dismissed notifications from the notification dropdown so that only unread notifications remain visible. Ensure a default message is displayed when all notifications are marked as read.

Review Checklist

• Marking notifications as read removes their visibility from the notification dropdown
• Read notifications are still seen on the Notifications page
• Necessary backend unit testing has been added
• Necessary frontend unit testing has been added
• Necessary integration testing has been added
• Documentation has been updated to reflect new changes

Accessibility Checklist

• No new color contrast issues are introduced
• Changed text has a font size of at least 16px
• Changed text uses plain language

[gmeben]

Feature Request: https://feedback.pilcrow.dev/posts/9/dismiss-all-remove-notifications-after-pressing

[sattler9]

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