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/exchange/client_flow_test.go

@@ -0,0 +1,52 @@
+package exchange
+
+import (
+	"context"
+	"crypto/rsa"
+	"math/rand"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap/zaptest"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/crypto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tdsync"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/transport"
+)
+
+func TestExchangeTimeout(t *testing.T) {
+	a := require.New(t)
+
+	reader := rand.New(rand.NewSource(1))
+	key, err := rsa.GenerateKey(reader, crypto.RSAKeyBits)
+	a.NoError(err)
+	log := zaptest.NewLogger(t)
+
+	i := transport.Intermediate
+	client, _ := i.Pipe()
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+
+	g := tdsync.NewCancellableGroup(ctx)
+	g.Go(func(ctx context.Context) error {
+		_, err := NewExchanger(client, 2).
+			WithLogger(log.Named("client")).
+			WithRand(reader).
+			WithTimeout(1 * time.Second).
+			Client([]PublicKey{
+				{
+					RSA: &key.PublicKey,
+				},
+			}).
+			Run(ctx)
+		return err
+	})
+
+	err = g.Wait()
+	var e net.Error
+	a.ErrorAs(err, &e)
+	a.True(e.Timeout())
+}