User: Make the user_login field readonly instead of disabled.

On the profile edit screen in ``wp-admin, the username was previously displayed using an input field with the `disabled` attribute. This field was skipped by screen readers, which leads to a loss of information for visually impaired users. This changeset switches it to a `readonly` attribute, which is exactly the purpose of this field.

Props roytanck, audrasjb, rajinsharwar, joedolson.
Fixes #60774.




git-svn-id: https://develop.svn.wordpress.org/trunk@58280 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/user-edit.php

@@ -438,7 +438,7 @@
 				<table class="form-table" role="presentation">
 					<tr class="user-user-login-wrap">
 						<th><label for="user_login"><?php _e( 'Username' ); ?></label></th>
-						<td><input type="text" name="user_login" id="user_login" value="<?php echo esc_attr( $profile_user->user_login ); ?>" disabled="disabled" class="regular-text" /> <span class="description"><?php _e( 'Usernames cannot be changed.' ); ?></span></td>
+						<td><input type="text" name="user_login" id="user_login" value="<?php echo esc_attr( $profile_user->user_login ); ?>" readonly="readonly" class="regular-text" /> <span class="description"><?php _e( 'Usernames cannot be changed.' ); ?></span></td>
 					</tr>
 
 					<?php if ( ! IS_PROFILE_PAGE && ! is_network_admin() && current_user_can( 'promote_user', $profile_user->ID ) ) : ?>