File: Add border block support

[akasunil]

What?

Add border block support to the File block.

Part of #43247

Why?

File block is missing border support.

How?

Adds the border block support in block.json

Testing Instructions

• Go to Global Styles setting ( under appearance > editor > styles > edit styles > blocks )
• Make sure that File block's border is configurable via Global Styles
• Verify that Global Styles are applied correctly in the editor and frontend
• Edit template/page, Add File block and Apply the border styles
• Verify that block styles take precedence over global styles
• Verify that block borders display correctly in both the editor and frontend

Watch attached video for more information.

Screenshots or screencast

file-block-border-support.webm

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: akasunil <[email protected]>
Co-authored-by: aaronrobertshaw <[email protected]>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[aaronrobertshaw]

Thanks for the continued efforts on border support adoption @akasunil 👍

✅ Global styles apply correctly
✅ Block instance styles override global styles
✅ Styles apply consistently between editor and frontend
✅ Box sizing allows parent to enforce width
✅ Default display of border controls matches spacing controls

LGTM 🚢

Screen.Recording.2024-08-19.at.4.20.30.PM.mp4