Editor: Deprecate _resolve_home_block_template().

The internal Core-only `_resolve_home_block_template()` function was introduced in [53093] for a specific purpose of resolving the template for a site's home page. It was used as part of the Site Editor's redirect when the `postType` and `postId` query args were missing. The server-side handling was removed in [55338]. The function is no longer used in Core.

This changeset deprecates the function and removes its tests.

Follow-up to [55338], [53093].

Props johnbillion, hellofromTonya.
Fixes #57716.

git-svn-id: https://develop.svn.wordpress.org/trunk@55436 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/deprecated.php

@@ -4591,3 +4591,39 @@ function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' )
 
 	return null;
 }
+
+/**
+ * Returns the correct template for the site's home page.
+ *
+ * @access private
+ * @since 6.0.0
+ * @deprecated 6.2.0 Site Editor's server-side redirect for missing postType and postId
+ *             		 query args is removed. Thus, this function is no longer used.
+ *
+ * @return array|null A template object, or null if none could be found.
+ */
+function _resolve_home_block_template() {
+	_deprecated_function( __FUNCTION__, '6.2.0' );
+
+	$show_on_front = get_option( 'show_on_front' );
+	$front_page_id = get_option( 'page_on_front' );
+
+	if ( 'page' === $show_on_front && $front_page_id ) {
+		return array(
+				'postType' => 'page',
+				'postId'   => $front_page_id,
+		);
+	}
+
+	$hierarchy = array( 'front-page', 'home', 'index' );
+	$template  = resolve_block_template( 'home', $hierarchy, '' );
+
+	if ( ! $template ) {
+		return null;
+	}
+
+	return array(
+			'postType' => 'wp_template',
+			'postId'   => $template->id,
+	);
+}