Column: Enable border radius support

[aaronrobertshaw]

Fixes: #41345

What?

Enables border-radius support for individual Column blocks.

Note: This PR does not add any automatic clipping of overflow content as discussed on the original issue. This will bring the Column block in line with the Group block.

Why?

To unlock more design possibilities and reduce the need for unnecessary wrapping of content in Group blocks to achieve the same end.

How?

Enable border-radius block support.

Testing Instructions

1. Open the site editor and navigate to Styles > Blocks > Column
2. Add a global border radius for Column blocks
3. Add some columns with background color to the page or post and ensure radius is displayed correctly
4. Save and confirm the radius is applied correctly on the frontend
5. Back in the editor select a Column block instance
6. Tweak that instance's border radii and confirm those values override the global styles
7. Save and confirm display on the frontend.

Screenshots or screencast

[github-actions]

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Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>
Co-authored-by: carolinan <poena@git.wordpress.org>
Co-authored-by: richtabor <richtabor@git.wordpress.org>
Co-authored-by: mikemcalister <mmcalister@git.wordpress.org>
Co-authored-by: maurodf0 <maurodf@git.wordpress.org>
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[carolinan]

I have followed the testing instructions and the radius is working as described. Thank you for the PR.

[richtabor]

Simple, performs just like the group block. Not overthinking it. Nice.

[aaronrobertshaw]

Thanks for the reviews and getting this one merged, appreciate it 🚀

[jeffpaul]

@gabrieltogan mind sharing your WordPress.org username so I can ensure its included in the 6.7 credits listing?