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/tgtest/test_transport.go

@@ -0,0 +1,88 @@
+package tgtest
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+type testTransportHandler struct {
+	t      testing.TB
+	logger *zap.Logger
+	// For ACK testing proposes.
+	// We send ack only after second request
+	counter   int
+	counterMx sync.Mutex
+
+	message string // immutable
+}
+
+// TestTransport is a handler for testing MTProto transport.
+func TestTransport(t testing.TB, logger *zap.Logger, message string) Handler {
+	return &testTransportHandler{
+		t:       t,
+		logger:  logger,
+		message: message,
+	}
+}
+
+func (h *testTransportHandler) OnMessage(server *Server, req *Request) error {
+	id, err := req.Buf.PeekID()
+	if err != nil {
+		return err
+	}
+
+	h.logger.Info("New message", zap.String("id", fmt.Sprintf("%#x", id)))
+
+	switch id {
+	case tg.UsersGetUsersRequestTypeID:
+		getUsers := tg.UsersGetUsersRequest{}
+
+		if err := getUsers.Decode(req.Buf); err != nil {
+			return err
+		}
+		h.logger.Info("New client connected, invoke received")
+
+		if err := server.SendVector(req, &tg.User{
+			ID:         10,
+			AccessHash: 10,
+			Username:   "rustcocks",
+		}); err != nil {
+			return err
+		}
+
+		h.logger.Info("Sending message", zap.String("message", h.message))
+		return server.SendUpdates(req.RequestCtx, req.Session, &tg.UpdateNewMessage{
+			Message: &tg.Message{
+				ID:      1,
+				PeerID:  &tg.PeerUser{UserID: 1},
+				Message: h.message,
+			},
+		})
+	case tg.MessagesSendMessageRequestTypeID:
+		m := &tg.MessagesSendMessageRequest{}
+		if err := m.Decode(req.Buf); err != nil {
+			h.t.Fail()
+			return err
+		}
+
+		assert.Equal(h.t, "какими деньгами?", m.Message)
+
+		h.counterMx.Lock()
+		h.counter++
+		if h.counter < 2 {
+			h.counterMx.Unlock()
+			return nil
+		}
+		h.counterMx.Unlock()
+
+		return server.SendResult(req, &tg.Updates{})
+	}
+
+	return nil
+}