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/query/internal/itergen/gen_test.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"testing"
+)
+
+func TestGenerate(t *testing.T) {
+	var out bytes.Buffer
+	if err := generate(context.Background(), &out, collectorConfig{
+		ResultName: "MessagesMessagesClass",
+		ElemName:   "Elem",
+		Prefix:     "Messages",
+		PkgName:    "messages",
+	}); err != nil {
+		t.Fatal(err)
+	}
+}