Code Editor: Improve ability to create Customizer CodeEditorControl instances in JS, lessening PHP dependencies.

Allow `CodeEditorControl` to be instantiated with a `editor_settings` param which is merged with `wp.codeEditor.defaultSettings`.

Also:

* Turn redundant "CSS Code" control label into screen reader text for Additional CSS.
* Remove `code-editor` as script dependency for `custom-html-widgets` since enqueueing is determined by `wp_enqueue_code_editor()`.
* Remove useless exporting of `code_type` param to JS in `WP_Customize_Code_Editor_Control`.
* Add `disabled` class to Custom HTML widget's Save button when linting errors are present.
* Remove redundant `span` inside CodeEditorControl's `label`.

See #41897, #12423, #41872.


git-svn-id: https://develop.svn.wordpress.org/trunk@41957 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/customize/class-wp-customize-code-editor-control.php

@@ -69,7 +69,6 @@ class WP_Customize_Code_Editor_Control extends WP_Customize_Control {
 	 */
 	public function json() {
 		$json = parent::json();
-		$json['code_type'] = $this->code_type;
 		$json['editor_settings'] = $this->editor_settings;
 		$json['input_attrs'] = $this->input_attrs;
 		return $json;
@@ -91,8 +90,8 @@ class WP_Customize_Code_Editor_Control extends WP_Customize_Control {
 		?>
 		<# var elementIdPrefix = 'el' + String( Math.random() ); #>
 		<# if ( data.label ) { #>
-			<label for="{{ elementIdPrefix }}_editor">
-				<span class="customize-control-title">{{ data.label }}</span>
+			<label for="{{ elementIdPrefix }}_editor" class="customize-control-title">
+				{{ data.label }}
 			</label>
 		<# } #>
 		<# if ( data.description ) { #>