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/mtproto/handle_future_salts_test.go

@@ -0,0 +1,52 @@
+package mtproto
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mt"
+)
+
+func TestConn_handleFutureSalts(t *testing.T) {
+	now := time.Now()
+	ts := int(now.Unix())
+	testdata := []mt.FutureSalt{
+		{
+			ValidSince: ts - 1,
+			ValidUntil: ts + 1,
+			Salt:       10,
+		},
+		{
+			ValidSince: ts + 1,
+			ValidUntil: ts + 3,
+			Salt:       11,
+		},
+	}
+
+	t.Run("OK", func(t *testing.T) {
+		a := require.New(t)
+		conn := Conn{log: zap.NewNop()}
+		buf := bin.Buffer{}
+
+		a.NoError(buf.Encode(&mt.FutureSalts{
+			ReqMsgID: 1,
+			Now:      1,
+			Salts:    testdata,
+		}))
+		a.NoError(conn.handleFutureSalts(&buf))
+
+		salt, ok := conn.salts.Get(now)
+		a.Equal(int64(10), salt)
+		a.True(ok)
+	})
+	t.Run("Invalid", func(t *testing.T) {
+		conn := Conn{}
+		buf := bin.Buffer{}
+		buf.PutID(mt.FutureSaltsTypeID)
+		require.Error(t, conn.handleFutureSalts(&buf))
+	})
+}