Fix 64-bit numeric enum values in typescript (#7135)

* Fix 64-bit default numeric enum values in typescript

If you had a default value that wasn't a valid enum value (e.g., a zero
if you used a bit_flag setting, like you get with AdvancedFeatures
in reflection.fbs), we weren't using BigInt.

* Run generate_code.py

* [DART] Handle deprecated fields & invalid enum defaults

* Update .NET test

tests/MyGame/Example/LongEnum.php

@@ -0,0 +1,25 @@
+<?php
+// automatically generated by the FlatBuffers compiler, do not modify
+
+namespace MyGame\Example;
+
+class LongEnum
+{
+    const LongOne = 2;
+    const LongTwo = 4;
+    const LongBig = 1099511627776;
+
+    private static $names = array(
+        LongEnum::LongOne=>"LongOne",
+        LongEnum::LongTwo=>"LongTwo",
+        LongEnum::LongBig=>"LongBig",
+    );
+
+    public static function Name($e)
+    {
+        if (!isset(self::$names[$e])) {
+            throw new \Exception();
+        }
+        return self::$names[$e];
+    }
+}