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/tdjson/errors.go

@@ -0,0 +1,24 @@
+package tdjson
+
+import (
+	"fmt"
+
+	"github.com/go-faster/errors"
+)
+
+// UnexpectedIDError means that unknown or unexpected type id was decoded.
+type UnexpectedIDError struct {
+	ID string
+}
+
+func (e *UnexpectedIDError) Error() string {
+	return fmt.Sprintf("unexpected id %s", e.ID)
+}
+
+// NewUnexpectedID return new UnexpectedIDError.
+func NewUnexpectedID(id string) error {
+	return &UnexpectedIDError{ID: id}
+}
+
+// ErrTypeIDNotFound means that @type field is expected, but not found.
+var ErrTypeIDNotFound = errors.New("@type field is expected, but not found")