fix/8363: Match editor "Place Order" button UI with frontend

[iamdharmesh]

PR makes changes in the checkout actions block to match the "Place Order" button UI with the front end.

Fixes #8363

Accessibility

• I've tested using only a keyboard (no mouse)
• I've tested using a screen reader
• All animations respect prefers-reduced-motion
• All text has at least a 4.5 color contrast with its background

Other Checks

• This PR adds/removes a feature flag & I've updated this doc.
• This PR adds/removes an experimental interfaces and I've updated this doc.
• I tagged two reviewers because this PR makes queries to the database or I think it might have some security impact.

Screenshots

Before	After

Testing

Automated Tests

• Changes in this PR are covered by Automated Tests.
  • Unit tests
  • E2E tests

User Facing Testing

1. Checkout to this PR branch.
2. Edit the "Checkout Block" page and Verify "Place Order" UI match with the front-end Place Order button UI.

• Do not include in the Testing Notes

WooCommerce Visibility

• WooCommerce Core
• Feature plugin
• Experimental

Performance Impact

Changelog

Match editor "Place Order" button UI with frontend

[nielslange]

Thank you so much for working on this, @iamdharmesh! 👏 I've successfully tested the PR using various block and non-block themes. I'll keep an eye on the tests, but I hope I can merge this PR in the next hours. 🙌

[qasumitbagthariya]

QA Update ✅

---

Testing Environment

• WordPress: 6.2
• Theme: Storefront 4.2.0
• Theme: Storefront 1.3.0
• Theme: Twenty Twenty-One 1.8
• Theme: Twenty Twenty-Three 1.1
• Theme: Twenty Twenty-Two 1.4
• Woocommerce - 7.6.0
• PHP: 8.0.21
• Web Server: Nginx 1.20.2
• Browser: Chrome
• OS: Windows 11
• Git Branch: testing

Theme - Storefront

Theme - Twenty Twenty-Three

Theme - Twenty Twenty-One

QA Status- Pass ✅

[mikejolley]

Tests are good, going ahead and merging this. Thanks @nielslange @qasumitbagthariya and @iamdharmesh