Add param type inferer based on passed arguments

[TomasVotruba]

<?php // fix

class A {
-  public function takesString($s) : void {
+  public function takesString(string $s) : void {
    echo $s;
  }
}

(new A)->takesString("hello");

Inpised by https://psalm.dev/articles/psalm-3-and-a-half