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/proto/codec/full_test.go

@@ -0,0 +1,40 @@
+package codec
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+)
+
+func fullTestData() (packet, payload []byte) {
+	return []byte{
+		15, 0, 0, 0, // length
+		1, 0, 0, 0, // seqNo
+		97, 98, 99, // payload
+		78, 214, 109, 148, // crc
+	}, []byte("abc")
+}
+
+func TestFull(t *testing.T) {
+	packet, payload := fullTestData()
+	t.Run("write", func(t *testing.T) {
+		b := bytes.NewBuffer(nil)
+
+		buf := &bin.Buffer{Buf: payload}
+		err := writeFull(b, 1, buf)
+		require.NoError(t, err)
+
+		require.Equal(t, packet, b.Bytes())
+	})
+
+	t.Run("read", func(t *testing.T) {
+		b := &bin.Buffer{}
+		err := readFull(bytes.NewBuffer(packet), 1, b)
+		require.NoError(t, err)
+
+		require.Equal(t, payload, b.Buf)
+	})
+}