Replace keys in Rich Text Editor blocks on clone operations

[lauraneto]

For BlockList and BlockGrid there are notification handlers that handle replacing the keys of blocks with new ones on copy of scaffolding. This was missing for the RTE blocks.
I did a few tests and couldn't see an issue with just re-using the same logic as for BlockList or BlockGrid, but let me know if there are any extra considerations that we should take in mind.

Testing

1. Create an element document type.
2. Create an RTE data type and configure it so blocks can be added, and add the element created in the previous step.
3. Create a document type, allowed at root, and add a property using the data type created in the previous step.
4. Create and publish a new page using the created document type and insert some content in the RTE with at least one block.
5. Check the keys of the blocks in the new page by either:

• Checking the response of the management API while requesting the document
  
• Checking the value of the property in the umbracoPropertyData database table

6. Make a copy of the page and check that the keys are different from the original.
7. Make a blueprint from the created page and create a new page using that blueprint. Check that the keys of the new page are different from the original.

[Copilot]

Pull Request Overview

Adds support for replacing block keys in Rich Text Editor (RTE) blocks during clone and scaffold operations by reusing the existing block editor notification logic.

• Introduces RichTextPropertyNotificationHandler to handle RTE block key replacement
• Registers the new handler for save, copy, and scaffold notifications

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
RichTextPropertyNotificationHandler.cs	Implements a notification handler for RTE block keys
UmbracoBuilder.CoreServices.cs	Registers the new handler in the core notification setup

Comments suppressed due to low confidence (2)

src/Umbraco.Infrastructure/DependencyInjection/UmbracoBuilder.CoreServices.cs:355

• There are no existing tests verifying that RTE block keys are replaced on copy/scaffold operations—adding unit or integration tests would help prevent regressions.

.AddNotificationHandler<ContentSavingNotification, RichTextPropertyNotificationHandler>()

src/Umbraco.Infrastructure/PropertyEditors/RichTextPropertyNotificationHandler.cs:20

• The Constants identifier is in the Umbraco.Cms.Core namespace but there's no using Umbraco.Cms.Core;—add the directive or fully qualify the reference.

protected override string EditorAlias => Constants.PropertyEditors.Aliases.RichText;

[AndyButland]

I've tested this out and it works as expected with the copy and blueprint operations.