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/thumbnail/thumbnail_test.go

@@ -0,0 +1,60 @@
+package thumbnail
+
+import (
+	"bytes"
+	"image/jpeg"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/testutil"
+)
+
+func TestExpand(t *testing.T) {
+	strippedImage := []byte{
+		0x01, 0x0e, 0x28, 0xa3, 0x9e, 0x05, 0x26, 0x78, 0xa5, 0x03, 0x8e, 0xb4, 0xd2, 0x31, 0x40, 0x06,
+		0x7d, 0x85, 0x19, 0xa4, 0xe2, 0x8e, 0x28, 0x00, 0xa2, 0x8a, 0x28, 0x03,
+	}
+
+	t.Run("Expand", func(t *testing.T) {
+		a := require.New(t)
+
+		to := make([]byte, 0, 1024)
+		testutil.ZeroAlloc(t, func() {
+			var err error
+			to, err = ExpandTo(strippedImage, to[:0])
+			a.NoError(err)
+		})
+
+		_, err := jpeg.Decode(bytes.NewReader(to))
+		a.NoError(err)
+	})
+	t.Run("ExpandTwice", func(t *testing.T) {
+		a := require.New(t)
+
+		result, err := Expand(strippedImage)
+		a.NoError(err)
+
+		offset := len(result)
+		result, err = ExpandTo(strippedImage, result)
+		a.NoError(err)
+
+		a.Equal(result[:offset], result[offset:])
+
+		_, err = jpeg.Decode(bytes.NewReader(result[:offset]))
+		a.NoError(err)
+
+		_, err = jpeg.Decode(bytes.NewReader(result[offset:]))
+		a.NoError(err)
+	})
+	t.Run("InvalidPrefix", func(t *testing.T) {
+		a := require.New(t)
+		_, err := ExpandTo([]byte{0x02, 0x0e, 0x28, 0xa3}, nil)
+		a.Error(err)
+	})
+	t.Run("InvalidLength", func(t *testing.T) {
+		a := require.New(t)
+		_, err := ExpandTo([]byte{1, 2}, nil)
+		a.Error(err)
+	})
+}