Blocks: Add support for the ancestor and parent settings for the block variation

[gigitux]

What problem does this address?

Part of #41236.

It would be very interesting to have support for the ancestor setting for the block variations.

In WooCommerce, we use a variation of the Query Loop block called Products. To be consistent with the naming and offer a good UI/UX, we created a variation of the Post Title called Product Title.

We can't limit the block visibility without the' ancestor' setting. Users can add the Product Title to a post/page block. Being a variation of the Post Title, the behavior is the same as this latter, but for the user could be weird.

What is your proposed solution?

Having the possibility to change the visibility of the variation via the ancestor setting fixes this use case.

[gziolo]

This is a great idea to include both features for block variations. There might be more features that we could share with variations but we would need to identify what'd make sense.

Thank you for opening this issue that is now tracked in #41236 with other planned tasks for Block API.