PHPCS: fix up the code base [2] - scope modifiers

Fixes relate to the following rules:
* Always specify visibility for all class properties and methods.

Author: jrfnl

src/Scaffold_Command.php

@@ -490,7 +490,7 @@ public function _s( $args, $assoc_args ) {
 	 *
 	 * @subcommand child-theme
 	 */
-	function child_theme( $args, $assoc_args ) {
+	public function child_theme( $args, $assoc_args ) {
 		$theme_slug = $args[0];
 
 		if ( in_array( $theme_slug, array( '.', '..' ) ) ) {
@@ -634,7 +634,7 @@ private function get_output_path( $assoc_args, $subdir ) {
 	 *     Success: Created plugin files.
 	 *     Success: Created test files.
 	 */
-	function plugin( $args, $assoc_args ) {
+	public function plugin( $args, $assoc_args ) {
 		$plugin_slug    = $args[0];
 		$plugin_name    = ucwords( str_replace( '-', ' ', $plugin_slug ) );
 		$plugin_package = str_replace( ' ', '_', $plugin_name );