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_result.go

@@ -0,0 +1,66 @@
+package mtproto
+
+import (
+	"github.com/go-faster/errors"
+	"go.uber.org/zap"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mt"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgerr"
+)
+
+func (c *Conn) handleResult(b *bin.Buffer) error {
+	// Response to an RPC query.
+	var res proto.Result
+	if err := res.Decode(b); err != nil {
+		return errors.Wrap(err, "decode")
+	}
+
+	// Now b contains result message.
+	b.ResetTo(res.Result)
+
+	msgID := zap.Int64("msg_id", res.RequestMessageID)
+	c.logWithBuffer(b).Debug("Handle result", msgID)
+
+	// Handling gzipped results.
+	id, err := b.PeekID()
+	if err != nil {
+		return err
+	}
+	if id == proto.GZIPTypeID {
+		content, err := gzip(b)
+		if err != nil {
+			return errors.Wrap(err, "decompress")
+		}
+
+		// Replacing buffer so callback will deal with uncompressed data.
+		b = content
+		c.logWithBuffer(b).Debug("Decompressed", msgID)
+
+		// Replacing id with inner id if error is compressed for any reason.
+		if id, err = b.PeekID(); err != nil {
+			return errors.Wrap(err, "peek id")
+		}
+	}
+
+	if id == mt.RPCErrorTypeID {
+		var rpcErr mt.RPCError
+		if err := rpcErr.Decode(b); err != nil {
+			return errors.Wrap(err, "error decode")
+		}
+
+		c.log.Debug("Got error", msgID,
+			zap.Int("err_code", rpcErr.ErrorCode),
+			zap.String("err_msg", rpcErr.ErrorMessage),
+		)
+		c.rpc.NotifyError(res.RequestMessageID, tgerr.New(rpcErr.ErrorCode, rpcErr.ErrorMessage))
+
+		return nil
+	}
+	if id == mt.PongTypeID {
+		return c.handlePong(b)
+	}
+
+	return c.rpc.NotifyResult(res.RequestMessageID, b)
+}