Move class-two-factor-core.php login styles from inline to enqueued stylesheet

[masteradhoc]

Step to achieve #63

What?

This PR removes the inline CSS block from the Two-Factor login screen and moves them to the user-edit.css stylesheet instead.

Why?

fix the outstanding TODO

How?

The login rendering flow now enqueues user-edit.css before outputting the login header, so the 2FA login UI receives the same styles via the stylesheet.

Testing Instructions

1. Enable the Two-Factor plugin and configure a 2FA provider for a test user.
2. Log out, then log in as that user to reach the 2FA challenge screen.
3. Confirm the styles still apply:

Screenshots or screencast

Changelog Entry

Changed - Load Two-Factor login screen styles from enqueued user-edit.css and remove duplicated inline CSS.

[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: masteradhoc <masteradhoc@git.wordpress.org>
Co-authored-by: georgestephanis <georgestephanis@git.wordpress.org>
Co-authored-by: dd32 <dd32@git.wordpress.org>

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

[georgestephanis]

Converting @to-do to @to-did? Nice.

I assume they aren't going to cause any conflicts with legacy usage of that file?

[dd32]

Should any of those CSS rules be tighter scoped?

[masteradhoc]

@dd32 what do you think about the changes here? that would tighten the scope better.

[masteradhoc]

Suggested change

	.input.authcode {
	letter-spacing: 0.3em;
	}
	.input.authcode::placeholder {
	opacity: 0.5;
	}
	#loginform .input.authcode {
	letter-spacing: 0.3em;
	}
	#loginform .input.authcode::placeholder {
	opacity: 0.5;
	}

[masteradhoc]

Suggested change

	.backup-methods-wrap {
	margin-top: 16px;
	padding: 0 24px;
	}
	.backup-methods-wrap a {
	text-decoration: none;
	}
	.backup-methods-wrap ul {
	list-style-position: inside;
	}
	#login .backup-methods-wrap {
	margin-top: 16px;
	padding: 0 24px;
	}
	#login .backup-methods-wrap a {
	text-decoration: none;
	}
	#login .backup-methods-wrap ul {
	list-style-position: inside;
	}