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/session/tdesktop/errors.go

@@ -0,0 +1,26 @@
+package tdesktop
+
+import (
+	"fmt"
+
+	"github.com/go-faster/errors"
+)
+
+// WrongMagicError is returned when tdesktop data file
+// has wrong magic header.
+type WrongMagicError struct {
+	Magic [4]byte
+}
+
+// Error implements error.
+func (w *WrongMagicError) Error() string {
+	return fmt.Sprintf("wrong magic %+v", w.Magic)
+}
+
+var (
+	// ErrKeyInfoDecrypt is returned when key data decrypt fails.
+	// It can happen if passed passcode is wrong.
+	ErrKeyInfoDecrypt = errors.New("key data decrypt")
+	// ErrNoAccounts reports that decoded tdata does not contain any accounts info.
+	ErrNoAccounts = errors.New("tdesktop data does not contain accounts")
+)