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/tgtest/services/config/config.go

@@ -0,0 +1,72 @@
+// Package config contains config service implementation for tgtest server.
+package config
+
+import (
+	"context"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgtest"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgtest/services"
+)
+
+// Service is a Telegram config service.
+type Service struct {
+	cfg    *tg.Config
+	cdnCfg *tg.CDNConfig
+}
+
+// NewService creates new Service.
+func NewService(cfg *tg.Config, cdnCfg *tg.CDNConfig) *Service {
+	return &Service{cfg: cfg, cdnCfg: cdnCfg}
+}
+
+func (c *Service) HelpGetCDNConfig(ctx context.Context, req *tg.HelpGetCDNConfigRequest) (*tg.CDNConfig, error) {
+	cfg := c.cdnCfg
+	return cfg, nil
+}
+
+func (c *Service) HelpGetConfig(ctx context.Context, dc int, req *tg.HelpGetConfigRequest) (*tg.Config, error) {
+	cfg := *c.cfg
+	cfg.ThisDC = dc
+	return &cfg, nil
+}
+
+// OnMessage implements tgtest.Handler.
+func (c *Service) OnMessage(server *tgtest.Server, req *tgtest.Request) error {
+	id, err := req.Buf.PeekID()
+	if err != nil {
+		return err
+	}
+
+	var (
+		decode bin.Decoder
+		result bin.Encoder
+	)
+	switch id {
+	case tg.HelpGetCDNConfigRequestTypeID:
+		cfg := c.cdnCfg
+
+		decode = &tg.HelpGetCDNConfigRequest{}
+		result = cfg
+	case tg.HelpGetConfigRequestTypeID:
+		cfg := *c.cfg
+		cfg.ThisDC = req.DC
+
+		decode = &tg.HelpGetConfigRequest{}
+		result = &cfg
+	default:
+		return services.ErrMethodNotImplemented
+	}
+
+	if err := decode.Decode(req.Buf); err != nil {
+		return err
+	}
+	return server.SendResult(req, result)
+}
+
+// Register registers service handlers.
+func (c *Service) Register(dispatcher *tgtest.Dispatcher) {
+	dispatcher.HandleFunc(tg.HelpGetCDNConfigRequestTypeID, c.OnMessage)
+	dispatcher.HandleFunc(tg.HelpGetConfigRequestTypeID, c.OnMessage)
+}