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/peer/singleflight.go

@@ -0,0 +1,52 @@
+package peer
+
+import (
+	"context"
+
+	"golang.org/x/sync/singleflight"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+type singleFlight struct {
+	next Resolver
+	sg   singleflight.Group
+}
+
+func (s *singleFlight) ResolveDomain(ctx context.Context, domain string) (tg.InputPeerClass, error) {
+	ch := s.sg.DoChan(domain, func() (interface{}, error) {
+		return s.next.ResolveDomain(ctx, domain)
+	})
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case r := <-ch:
+		if r.Err != nil {
+			return nil, r.Err
+		}
+		return r.Val.(tg.InputPeerClass), nil
+	}
+}
+
+func (s *singleFlight) ResolvePhone(ctx context.Context, phone string) (tg.InputPeerClass, error) {
+	ch := s.sg.DoChan(phone, func() (interface{}, error) {
+		return s.next.ResolvePhone(ctx, phone)
+	})
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case r := <-ch:
+		if r.Err != nil {
+			return nil, r.Err
+		}
+		return r.Val.(tg.InputPeerClass), nil
+	}
+}
+
+// SingleflightResolver is a simple resolver decorator
+// which prevents duplicate resolve calls.
+func SingleflightResolver(next Resolver) Resolver {
+	return &singleFlight{next: next}
+}