move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/internal/manager/connmode_string.go

@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=ConnMode"; DO NOT EDIT.
+
+package manager
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ConnModeUpdates-0]
+	_ = x[ConnModeData-1]
+	_ = x[ConnModeCDN-2]
+}
+
+const _ConnMode_name = "ConnModeUpdatesConnModeDataConnModeCDN"
+
+var _ConnMode_index = [...]uint8{0, 15, 27, 38}
+
+func (i ConnMode) String() string {
+	if i >= ConnMode(len(_ConnMode_index)-1) {
+		return "ConnMode(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _ConnMode_name[_ConnMode_index[i]:_ConnMode_index[i+1]]
+}