Add automated test for "Insert an Icon Macro in CKEditor"

The manual test is here: Insert Icon Macro [Since XWiki 14.10.6]

The test verifies that the Icon Macro can be inserted in CKEditor and works as expected.

Matrix discussion: https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$1682075588419CQYVj:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=mtrx.nz

Ilie Andriuta: One more question: I was testing https://jira.xwiki.org/browse/XWIKI-20682 and I wanted to know if we have automated tests for Icon Macro
if we don't, I should write a manual test for it
Michael Hamann@mhamann:matrix.xwiki.com: 
There are various tests in https://github.com/xwiki/xwiki-platform/tree/46b542854978e9caa687a5c2b8817b8b17877d94/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-macro/src/test but they are rendering tests.
Further, if you open, e.g., the home page of the wiki, you're implicitly testing that the icon macro works (as it is triggered by the icon script service).
What's not really tested I think is inserting an icon macro in the WYSIWYG editor.
Not sure if that's something we're normally testing.
Ilie Andriuta: yes, that was my main case I was thinking of

Michael Hamann@mhamann:matrix.xwiki.com: 
And that insertion part could actually also be improved, we have an icon picker but it is currently not used as it wasn't that easy to integrate.
Ilie Andriuta: I understand, ok
I will create a test for inserting it in CKEditor and create a task for automation to have one