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/my-game/example/long-enum.ts

@@ -0,0 +1,8 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+export enum LongEnum{
+  LongOne = '2',
+  LongTwo = '4',
+  LongBig = '1099511627776'
+}
+