Editor: Fix 'wp-block-library-theme' style enqueue conditions.

Fixes the conditions for when to enqueue the opinionated block styles (i.e. `'wp-block-library-theme'` stylesheet):

* the theme adds `'wp-block-styles'` theme support;
* and no editor styles are declared.

This resolves an issue with themes that do not add the `'wp-block-styles'` theme support while not impacting themes that do.

Follow-up to [53419], [52069], [50761], [44157].

Props mikachan, costdev, glendaviesnz, hellofromTonya, jffng, mamaduka, ndiego, poena, sannevndrmeulen, scruffian.
Fixes #57561.
Built from https://develop.svn.wordpress.org/trunk@55368


git-svn-id: http://core.svn.wordpress.org/trunk@54901 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/site-editor.php

@@ -120,7 +120,7 @@ wp_enqueue_style( 'wp-format-library' );
 wp_enqueue_media();
 
 if (
-	current_theme_supports( 'wp-block-styles' ) ||
+	current_theme_supports( 'wp-block-styles' ) &&
 	( ! is_array( $editor_styles ) || count( $editor_styles ) === 0 )
 ) {
 	wp_enqueue_style( 'wp-block-library-theme' );