Hotfix: Block inline editing — create block variant

[nielslyngsoe]

Adding UI to expose an inline block — fixing inline mode for Block Editors.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (minor updates related to the tooling or maintenance of the repository, does not impact compiled assets)

Motivation and context

How to test?

• Create a variant block.
• See that it is auto exposed on the current variant.
• See that there is a button on other variants
• Click it to see that it gets exposed on that specific variant.

Screenshots (if appropriate)

Checklist

• If my change requires a change to the documentation, I have updated the documentation in this pull request.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.