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/peers/supergroup.go

@@ -0,0 +1,58 @@
+package peers
+
+import (
+	"context"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+// Supergroup is a supergroup Channel.
+type Supergroup struct {
+	Channel
+}
+
+// SlowmodeEnabled whether slow mode is enabled for groups to prevent flood in chat.
+func (c Supergroup) SlowmodeEnabled() bool {
+	return c.raw.GetSlowmodeEnabled()
+}
+
+// DisableSlowMode disables slow mode.
+func (c Supergroup) DisableSlowMode(ctx context.Context) error {
+	return c.ToggleSlowMode(ctx, -1)
+}
+
+// ToggleSlowMode Toggle supergroup slow mode: if enabled, users will only be able to send one message per seconds.
+//
+// If seconds is zero or smaller, slow mode will be disabled.
+func (c Supergroup) ToggleSlowMode(ctx context.Context, seconds int) error {
+	if seconds < 0 {
+		seconds = 0
+	}
+	if _, err := c.m.api.ChannelsToggleSlowMode(ctx, &tg.ChannelsToggleSlowModeRequest{
+		Channel: c.InputChannel(),
+		Seconds: seconds,
+	}); err != nil {
+		return errors.Wrap(err, "toggle slow mode")
+	}
+
+	return nil
+}
+
+// SetStickerSet associates a sticker set to this supergroup.
+func (c Supergroup) SetStickerSet(ctx context.Context, set tg.InputStickerSetClass) error {
+	if _, err := c.m.api.ChannelsSetStickers(ctx, &tg.ChannelsSetStickersRequest{
+		Channel:    c.InputChannel(),
+		Stickerset: set,
+	}); err != nil {
+		return errors.Wrap(err, "set stickers")
+	}
+
+	return nil
+}
+
+// ResetStickerSet resets associated sticker set of this supergroup.
+func (c Supergroup) ResetStickerSet(ctx context.Context) error {
+	return c.SetStickerSet(ctx, &tg.InputStickerSetEmpty{})
+}