Code Modernization: Fix parameter name mismatches for parent/child classes in WP_Customize_Setting::update().

In each child class: renames the parameter to match the parent's method signature.

Why? PHP 8 introduces the ability to pass named arguments to function/method calls. This means the child and parent method signatures (i.e. parameter names) need to match.

Changes for readability:

- `@since` clearly specifies the original parameter name and its new name as well as why the change happened.

- In methods longer than a single line, the generic parameter is reassigned to the original parameter restoring it for context for use within the method. An inline comment is added to explain why this reassignment is made.

Follow-up to [19995], [21037], [21053], [21354], [38829], [51298].

Props jrf, hellofromTonya, sergeybiryukov, azaozz, desrosj, johnbillion.
See #51553.

git-svn-id: https://develop.svn.wordpress.org/trunk@51784 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/customize/class-wp-customize-header-image-setting.php

@@ -24,7 +24,7 @@ final class WP_Customize_Header_Image_Setting extends WP_Customize_Setting {
 	 *
 	 * @global Custom_Image_Header $custom_image_header
 	 *
-	 * @param mixed $value
+	 * @param mixed $value The value to update.
 	 */
 	public function update( $value ) {
 		global $custom_image_header;