BellLayout: Hide potentially IE-breaking grid CSS behind `@supports`

most properties are just ignored, but not setting an IE-supported display property meant the X for deleting bells never showed up.

What does this MR do?

implement a fallback layout for IE11

How confident are you it won't break things if deployed?

100%.

Links to related issues

• slack: https://yunity.slack.com/archives/C74JC2V26/p1593071381019000
• commit reference: 9cfd6935
• see also: #907 (closed)

How to test

1. Generate some bells
2. Look at them in IE
3. Hover them in IE
4. Look at them in an actual browser
5. Hover them in an actual browser

Screenshots (if applicable)

no changes to the layout in actual browsers

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings