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/flood_wait_test.go

@@ -0,0 +1,22 @@
+package telegram_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/go-faster/errors"
+	"github.com/stretchr/testify/assert"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgerr"
+)
+
+func TestAsFloodWait(t *testing.T) {
+	err := func() error {
+		return errors.Wrap(tgerr.New(400, "FLOOD_WAIT_10"), "perform operation")
+	}()
+
+	d, ok := telegram.AsFloodWait(err)
+	assert.True(t, ok)
+	assert.Equal(t, time.Second*10, d)
+}