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.go

@@ -0,0 +1,32 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package Example
+
+import "strconv"
+
+type LongEnum uint64
+
+const (
+	LongEnumLongOne LongEnum = 2
+	LongEnumLongTwo LongEnum = 4
+	LongEnumLongBig LongEnum = 1099511627776
+)
+
+var EnumNamesLongEnum = map[LongEnum]string{
+	LongEnumLongOne: "LongOne",
+	LongEnumLongTwo: "LongTwo",
+	LongEnumLongBig: "LongBig",
+}
+
+var EnumValuesLongEnum = map[string]LongEnum{
+	"LongOne": LongEnumLongOne,
+	"LongTwo": LongEnumLongTwo,
+	"LongBig": LongEnumLongBig,
+}
+
+func (v LongEnum) String() string {
+	if s, ok := EnumNamesLongEnum[v]; ok {
+		return s
+	}
+	return "LongEnum(" + strconv.FormatInt(int64(v), 10) + ")"
+}