Add Composer autoloading functions and PHPStan for testing

vendor/phpstan/phpdoc-parser/src/Ast/ConstExpr/ConstExprStringNode.php

@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\PhpDocParser\Ast\ConstExpr;
+
+class ConstExprStringNode implements ConstExprNode
+{
+
+	/** @var string */
+	public $value;
+
+	public function __construct(string $value)
+	{
+		$this->value = $value;
+	}
+
+
+	public function __toString(): string
+	{
+		return $this->value;
+	}
+
+}