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/transport/detect_codec_test.go

@@ -0,0 +1,70 @@
+package transport
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto/codec"
+)
+
+func Test_detectCodec(t *testing.T) {
+	tests := []struct {
+		name       string
+		data       []byte
+		resultType Codec
+		wantErr    bool
+	}{
+		{
+			"Abridged",
+			codec.AbridgedClientStart[:],
+			codec.Abridged{},
+			false,
+		},
+		{
+			"Intermediate",
+			codec.IntermediateClientStart[:],
+			codec.Intermediate{}, false,
+		},
+		{
+			"PaddedIntermediate",
+			codec.PaddedIntermediateClientStart[:],
+			codec.PaddedIntermediate{},
+			false,
+		},
+		{
+			"Full",
+			[]byte{'g', 'o', 't', 'd'},
+			&codec.Full{},
+			false,
+		},
+		{
+			"EOF-first",
+			nil,
+			nil,
+			true,
+		},
+		{
+			"EOF-second",
+			[]byte{'a'},
+			nil,
+			true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			a := require.New(t)
+
+			r, _, err := detectCodec(bytes.NewReader(test.data))
+			if test.wantErr {
+				a.Nil(r)
+				a.Error(err)
+			} else {
+				a.NotNil(r)
+				a.NoError(err)
+				a.IsType(test.resultType, r)
+			}
+		})
+	}
+}