Adapt close-hovering icon for notification API

[HeikoKlare]

The close icon for showing notifications has been adapted with a more modern look and feel. The "active" version of the icon, used when hovering over it, is currently still the old one and does not fit the new icon anymore.

This change introduces a new "active" version of the notification close icon, being a thicker version of the non-active one.

Fixes #2043

How it looks like

PR for images repo

Here is the according PR for the images repo: eclipse-platform/eclipse.platform.images#82

[HeikoKlare]

@vogella @BeckerWdf may I ask you for feedback on this? Do you consider this is proper and intuitive way of providing hovering feedback (in the context of such a popup)?

[github-actions]

Test Results

 1 815 files  ±0   1 815 suites  ±0   1h 29m 19s ⏱️ - 2m 43s
 7 663 tests ±0   7 435 ✅ +1  228 💤 ±0  0 ❌  - 1 
24 150 runs  ±0  23 401 ✅ +1  749 💤 ±0  0 ❌  - 1 

Results for commit 858c0ec. ± Comparison against base commit 44dc49e.

[BeckerWdf]

@vogella @BeckerWdf may I ask you for feedback on this? Do you consider this is proper and intuitive way of providing hovering feedback (in the context of such a popup)?

I like it!! 👍

[vogella]

Perfect, thanks for this.

[HeikoKlare]

Thanks for your feedback! Then I'll merge this together with the images repo PR eclipse-platform/eclipse.platform.images#82

Since it's only an icon exchange, I do not rebase on master and trigger an unnecessary build before merging.

[vogella]

Thanks @HeikoKlare re for this work (including providing the icon). I hope that we will see the notification API used more often in the future. For example, the restart dialog after an installation operation might be a good candidate for non-blocking notification.