Add PHP file_exists (#461)

* Add PHP file_exists

* Update src/php/filesystem/file_exists.js

---------

Co-authored-by: Kevin van Zonneveld <vanzonneveld@gmail.com>

src/php/filesystem/file_exists.js

@@ -0,0 +1,11 @@
+module.exports = function file_exists(filename) {
+  //       discuss at: https://locutus.io/php/file_exists/
+  //      original by: Erik Niebla
+  //           note 1: so this function is Node-only
+  //        example 1: file_exists('test/never-change.txt')
+  //        returns 1: true
+
+  const fs = require('fs')
+
+  return fs.existsSync(filename)
+}

src/php/filesystem/index.js

@@ -1,5 +1,6 @@
 module.exports.basename = require('./basename')
 module.exports.dirname = require('./dirname')
+module.exports.file_exists = require('./file_exists')
 module.exports.file_get_contents = require('./file_get_contents')
 module.exports.pathinfo = require('./pathinfo')
 module.exports.realpath = require('./realpath')