Check more files to determine if WordPress is present or not (#233)

* fix: Add user confirmation for re-download the WordPress

Added the user confirmation prompt while re-downloading the WordPress core files when user have alerady downloaded. Also added the modified version to check multiple WordPress files so that it does not have dependency on `wp-load.php` file.

* Feat: Add some file checks before redownloading the WordPress

Author: hbhalodia

src/Core_Command.php

@@ -137,7 +137,11 @@ public function download( $args, $assoc_args ) {
 			? ( rtrim( $assoc_args['path'], '/\\' ) . '/' )
 			: ABSPATH;
 
-		$wordpress_present = is_readable( $download_dir . 'wp-load.php' );
+		// Check for files if WordPress already present or not.
+		$wordpress_present = is_readable( $download_dir . 'wp-load.php' )
+			|| is_readable( $download_dir . 'wp-mail.php' )
+			|| is_readable( $download_dir . 'wp-cron.php' )
+			|| is_readable( $download_dir . 'wp-links-opml.php' );
 
 		if ( $wordpress_present && ! Utils\get_flag_value( $assoc_args, 'force' ) ) {
 			WP_CLI::error( 'WordPress files seem to already be present here.' );