Customize: Allow controls to be created with pre-instantiated Setting object(s), or even with plain Value object(s).

* Allow passing settings in keyed object (e.g. `settings: { default: 'id' }  ), or as an array (e.g. `settings: [ 'id' ]`) with first being default; again, `Setting`/`Value` objects may be supplied instead of IDs.
* Allow a single setting to be supplied with just a single `setting` param, either a string or a `Setting`/`Value` object.
* Update `changeset_status` and `scheduled_changeset_date` to be added dynamically with JS and simply passing of `api.state()` instances as `setting`.
* Introduce a `data-customize-setting-key-link` attribute which, unlike `data-customize-setting-link`, allows passing the setting key (e.g. `default`) as opposed to the setting ID.
* Allow `WP_Customize_Control::get_link()` to return `data-customize-setting-key-link` when setting is not registered.
* Eliminate `default_value` from `WP_Customize_Date_Time_Control` since now comes from supplied `Value`.
* Export status choices as `wp.customize.settings.changeset.statusChoices`.
* Export date and time formats as `wp.customize.settings.dateFormat` and `wp.customize.settings.timeFormat` respectively.

Props westonruter, sayedwp.
See #39896, #30738, #30741, #42083.
Fixes #37964, #36167.


git-svn-id: https://develop.svn.wordpress.org/trunk@41750 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -566,6 +566,7 @@ function wp_default_scripts( &$scripts ) {
 		'saved'              => __( 'Saved' ),
 		'cancel'             => __( 'Cancel' ),
 		'close'              => __( 'Close' ),
+		'action'             => __( 'Action' ),
 		'cheatin'            => __( 'Cheatin’ uh?' ),
 		'notAllowed'         => __( 'Sorry, you are not allowed to customize this site.' ),
 		'previewIframeTitle' => __( 'Site Preview' ),
@@ -594,6 +595,7 @@ function wp_default_scripts( &$scripts ) {
 			_n_noop( 'Unable to save due to %s invalid setting.', 'Unable to save due to %s invalid settings.' ),
 			array( 'singular', 'plural' )
 		),
+		'scheduleDescription' => __( 'Schedule your customization changes to publish ("go live") at a future date.' ),
 	) );
 	$scripts->add( 'customize-selective-refresh', "/wp-includes/js/customize-selective-refresh$suffix.js", array( 'jquery', 'wp-util', 'customize-preview' ), false, 1 );