The WordPress core password reset needs to pre-populate the username to meet WCAG 2.2

[rinkalpagdar]

Trac ticket: https://core.trac.wordpress.org/ticket/60726

This PR prepopulate the username into the login form after the password reset using the existing query parameter.

[github-actions]

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[github-actions]

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[pratik-londhe4]

I've tested the above patch locally, and it seems to be working as expected. The username is pre-populated when the user resets their password and navigates to the login page afterward.

[peterwilsoncc]

Please see my note on the original PR implimenting this change, it duplicates the issues discussed there.

#6928 (comment)

[joedolson]

I've updated the PR to address feedback by @westonruter and @peterwilsoncc; could use a review.

[westonruter]

While it's unlikely that a username will have a character which will get slashed, this seems like a best practice:

Suggested change

	setcookie( 'wp_user_login', sanitize_text_field( $_GET['user_login'] ), 0, COOKIEPATH, COOKIE_DOMAIN, $secure, true );
	setcookie( 'wp_user_login', sanitize_text_field( wp_unslash( $_GET['user_login'] ) ), 0, COOKIEPATH, COOKIE_DOMAIN, $secure, true );

[westonruter]

Is there another more specific function used for sanitizing usernames than sanitize_text_field()?