Fix SSO button display in RTL

[psorensen]

Description of the Change

Fixes the SSO login button layout when the site uses RTL (right-to-left) by adding RTL-specific padding.

The SSO button uses asymmetric padding (4px 14px 4px 4px) so the icon sits correctly in LTR. In RTL, that same padding caused incorrect spacing.

Benefits: Correct appearance and usability of the SSO button for RTL languages and RTL themes.
Before:

After:

How to test the Change

1. Open the WordPress login page (e.g. /wp-login.php) with the 10up Experience plugin active and SSO enabled.
2. LTR: Confirm the SSO ("Sign in with 10up" / Google) button looks and aligns as before.
3. RTL: Force RTL (e.g. in DevTools set document.documentElement.dir = 'rtl' or use an RTL theme/locale) and reload the login page.
4. Confirm the SSO button has even padding and the icon and label are not clipped or misaligned.

Changelog Entry

Fixed - SSO login button padding in RTL so the button displays correctly for right-to-left languages and layouts.

Credits

Props @psorensen

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.