Review behavior of existing features on multi-range selections in tables

[jodator]

📝 Provide a description of the improvement

Most of the CKEditor 5 features are already implemented with multi-range selection in mind or they operate on multiple nodes by default. However, as we introduce a multi-range selection as a supported solution in the model, we must check how features integrate with such a selection.

Add integration tests for the existing features that will validate that existing CKEditor 5 features works with a selected table fragment (multi-range selection).

Requires #6113.

---

If you'd like to see this improvement implemented, add a 👍 reaction to this post.

[Reinmar]

May be blocked by #6328.

[oleq]

Features broken so far when executed on a multi-cell selection (they crash):

• horizontal line
• page break
• special characters,
• pasting

I checked some of them and it mostly comes down to the InputCommand working on the first range only and passing a selection based on that range to Model#deleteContent which does not allow the TableSelection hook to kick in.

If we fixed that, then the Model#insertContent would also probably fail, but this is another issue.