fixed invalid TS call and added test files (#6495)

e581013e3d broke TS generation - please don't use "replace" to refactor function names :)

tests/optional_scalars/optional-byte.ts

@@ -0,0 +1,8 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+export enum OptionalByte{
+  None = 0,
+  One = 1,
+  Two = 2
+}
+