* Fix content visibility block. Attributes must be match server side …

[MaximilianoRicoTabo]

…and client side.

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• Have you followed the Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

• Add server side the attributes that were added to core widgets in the client side.

Resolves XXX.

How to test the changes in this Pull Request:

1. In order to reproduce log as an admin user
2. Appereace -> widget
3. Add cloud-tag block
4. Without this fix it will break.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?

Changelog entry

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.

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