added support for property promotion

[i582]

RFC: https://wiki.php.net/rfc/constructor_promotion

Declaring class properties in constructor parameters is syntactic sugar, so it matches very well with the code that we are compiling now.
In fact, the following conversion process is currently taking place:

From:

class Test {
    public function __construct(public Type $prop = DEFAULT) {}
}

To:

class Test {
    public Type $prop;
 
    public function __construct(Type $prop = DEFAULT) {
        $this->prop = $prop;
    }
}

#290