MDL-82424 behat: steps to handle plugins

This commit adds one new step to disable plugins, and also replaces the
regexp from the enable plugins method to make ti compatible with the
tool_generator create testing scenario.

lib/tests/behat/behat_general.php

@@ -2371,6 +2371,18 @@ EOF;
         $class::enable_plugin($plugin, true);
     }
 
+    /**
+     * Disable an specific plugin.
+     *
+     * @When /^I disable "(?P<plugin_string>(?:[^"]|\\")*)" "(?P<plugintype_string>[^"]*)" plugin$/
+     * @param string $plugin Plugin we look for
+     * @param string $plugintype The type of the plugin
+     */
+    public function i_disable_plugin($plugin, $plugintype) {
+        $class = core_plugin_manager::resolve_plugininfo_class($plugintype);
+        $class::enable_plugin($plugin, false);
+    }
+
     /**
      * Set the default text editor to the named text editor.
      *