Featured image: Add border style support

[carolinan]

What?

Revisit the decision to not include the border style support for the featured image block.
It is believed that the border style support was originally omitted so that the featured image block would match the settings on the image block.

Partial for
#47401
#43247

Testing Instructions

Test the border style options with different featured image block settings and when the block:

1. is a placeholder
2. is nested
3. is linked
4. is aligned
5. has duotone
6. has overlay

Style the block both from the Styles sidebar in the Site Editor and in the block editor.

[github-actions]

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Co-authored-by: carolinan <[email protected]>

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