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/message/builder_test.go

@@ -0,0 +1,38 @@
+package message
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func TestBuilder(t *testing.T) {
+	a := require.New(t)
+	b := new(Builder)
+
+	b = b.Silent()
+	a.True(b.silent)
+
+	b = b.Background()
+	a.True(b.background)
+
+	b = b.Clear()
+	a.True(b.clearDraft)
+
+	b = b.NoWebpage()
+	a.True(b.noWebpage)
+
+	b = b.ReplyMsg(&tg.Message{ID: 10})
+	a.Equal(10, b.replyTo.(*tg.InputReplyToMessage).ReplyToMsgID)
+
+	date := time.Now()
+	b = b.Schedule(date)
+	a.Equal(int(date.Unix()), b.scheduleDate)
+
+	markup := &tg.ReplyInlineMarkup{}
+	b = b.Markup(markup)
+	a.Equal(markup, b.replyMarkup)
+}