[Bug] Can't delete/activate a specific grouped notification with keyboard only

[ArijanJ]

Describe the bug
There is currently no way to delete a single notification through backspace/enter/arrow keys if they are grouped. Trying to delete it with backspace/del will delete every single notification in the grouping

To Reproduce
Steps to reproduce the behavior:

1. Receive multiple grouped notifications
2. Attempt to delete only one of them

Expected behavior
There should be a way to do this without using the mouse, as the non-grouped versions work perfectly and have good UX

Desktop (please complete the following information):

• OS: Mint w/ sway
• Version: latest git revision as of today