fix: return HTML instead of HtmlPageCrawler object (#1832)

Update the filters that use an HtmlPageCrawler to return the
outerHTML of the HtmlPageCrawler, rather than the object.

This will fix the regression seen with the WordPress 6.6
release that is causing those filters to fail with a fatal
error.

wordpress/wp-content/themes/cds-redirector/filter-core-buttons.php

@@ -23,7 +23,7 @@ function cds_filter_core_buttons($block_content, $block)
                 $links .= $link;
             }
 
-            return $links;
+            return $links->outerHtml();
         } catch (Exception $e) {
             //no-op
         }

wordpress/wp-content/themes/cds-website-preview/filter-core-image.php

@@ -11,7 +11,7 @@ function cds_filter_core_image($block_content, $block)
             // add the following styles to prevent the image from being improperly sized
             $img_html->css('max-width', '100%');
             $img_html->css('height', 'auto');
-            return $img_html;
+            return $img_html->outerHtml();
         } catch (Exception $e) {
             //no-op
         }