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.kt

@@ -0,0 +1,12 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+package MyGame.Example
+
+@Suppress("unused")
+class LongEnum private constructor() {
+    companion object {
+        const val LongOne: ULong = 2UL
+        const val LongTwo: ULong = 4UL
+        const val LongBig: ULong = 1099511627776UL
+    }
+}