This commit adds to the experimental user menu a new "other notifications" tab that's very similar to the "all notifications" tab, but with the main difference being that it doesn't show notification types that do have dedicated tabs in the menu (e.g. mentions, likes, replies etc.).
The rationale behind this is that the notification types that do have dedicated tabs tend to dominate the "all notifications" tab, leaving very small chances for the user to notice rarer or infrequent notification types. Adding a tab for all the other types gives the user a way to review those infrequent notification types.
Internal ticket: t72978.
Co-authored-by: OsamaSayegh <asooomaasoooma90@gmail.com>
Note this commit also introduce a new {{d-popover}} component, example usage:
```hbs
{{#d-popover |state|}}
{{d-button label="foo.things" class="d-popover-trigger"}}
<div class="d-popover-content">
Some content
<div>
{{/d-popover}}
```
Adds a custom bookmark-clock icon to discourse-additional.svg for use with the new bookmarks with reminder functionality.
Also add some code to correctly refresh the post-stream icon for bookmark to show the clock after save.