Widgets: Introduce media widgets for images, audio, and video with extensible base for additional media widgets in the future.

The last time a new widget was introduced, Vuvuzelas were a thing, Angry Birds started taking over phones, and WordPress stopped shipping with Kubrick. Seven years and 17 releases without new widgets have been enough, time to spice up your sidebar!

Props westonruter, melchoyce, obenland, timmydcrawford, adamsilverstein, gonom9, wonderboymusic, Fab1en, DrewAPicture, sirbrillig, joen, matias, samikeijonen, afercia, celloexpressions, designsimply, michelleweber, ranh, kjellr, karmatosed.
Fixes #32417, #39993, #39994, #39995.


git-svn-id: https://develop.svn.wordpress.org/trunk@40640 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/media-template.php

@@ -608,7 +608,7 @@ function wp_print_media_templates() {
 		<h2><?php _e( 'Attachment Display Settings' ); ?></h2>
 
 		<# if ( 'image' === data.type ) { #>
-			<label class="setting">
+			<label class="setting align">
 				<span><?php _e('Alignment'); ?></span>
 				<select class="alignment"
 					data-setting="align"
@@ -1087,7 +1087,7 @@ function wp_print_media_templates() {
 					</div>
 				</div>
 
-				<label class="setting checkbox-setting">
+				<label class="setting checkbox-setting autoplay">
 					<input type="checkbox" data-setting="autoplay" />
 					<span><?php _e( 'Autoplay' ); ?></span>
 				</label>
@@ -1176,7 +1176,7 @@ function wp_print_media_templates() {
 					</div>
 				</div>
 
-				<label class="setting checkbox-setting">
+				<label class="setting checkbox-setting autoplay">
 					<input type="checkbox" data-setting="autoplay" />
 					<span><?php _e( 'Autoplay' ); ?></span>
 				</label>