MDL-78175 output: new paragraph renderer method

Many main php files still uses html_writer('p...) to render a simple
paragraphs below or under other elements like forms. In many cases those
texts could be part of a template but there are may scenarios were
creating a full template for a simple paragraph is too much. However,
the html_writer is too limiting as plugins cannot provide their own
implementation. This new method in the renderer is a good in between
solution.

lib/outputrenderers.php

@@ -3263,6 +3263,22 @@ EOD;
         return $this->opencontainers->pop('box');
     }
 
+    /**
+     * Outputs a paragraph.
+     *
+     * @param string $contents The contents of the paragraph
+     * @param string|null $classes A space-separated list of CSS classes
+     * @param string|null $id An optional ID
+     * @return string the HTML to output.
+     */
+    public function paragraph(string $contents, ?string $classes = null, ?string $id = null): string {
+        return html_writer::tag(
+            'p',
+            $contents,
+            ['id' => $id, 'class' => renderer_base::prepare_classes($classes)]
+        );
+    }
+
     /**
      * Outputs a container.
      *