Add automated test for "In-line macro content editing"

The manual test is here: In-line macro content editing

Existing automated coverage

• MacroIT#editInlineParametersWithTheMacroEditModal: Edits the info macro title parameter and content in-line (macro set via Source); checks the values in the macro edit modal and the source.
• RealtimeWYSIWYGEditorIT#inplaceEditableMacro: Info Box content edited in-line, saved; asserts view-mode content.

Missing automated coverage

• Add a CKEditor page object for Insert > Other Macros (MacroDialogSelectModal exists but no CKEditor test opens it).
• Open Insert > Other Macros, search and select "Info Message", fill Title "This is a title!" and Content "This is an info macro!", Submit.
• Type extra words in-line after the content text and after the title text.
• Select words in the content and apply Bold, Italic and Underline.
• Save & View and assert the info box shows the updated title and content with the bold/italic/underline formatting.

Suggested location: xwiki-platform-core/xwiki-platform-ckeditor/xwiki-platform-ckeditor-test/xwiki-platform-ckeditor-test-docker/src/test/it/org/xwiki/ckeditor/test/ui/MacroIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).