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/tgmock/invoke.go

@@ -0,0 +1,35 @@
+package tgmock
+
+import (
+	"context"
+	"crypto/rand"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/crypto"
+)
+
+// Invoke implements tg.Invoker.
+func (i *Mock) Invoke(ctx context.Context, input bin.Encoder, output bin.Decoder) error {
+	h := i.Handler()
+
+	id, err := crypto.RandInt64(rand.Reader)
+	if err != nil {
+		return errors.Wrap(err, "generate id")
+	}
+
+	body, err := h(id, input)
+	if err != nil {
+		return errors.Wrap(err, "mock invoke")
+	}
+
+	buf := new(bin.Buffer)
+	if err := body.Encode(buf); err != nil {
+		return errors.Wrap(err, "encode")
+	}
+	if err := output.Decode(buf); err != nil {
+		return errors.Wrap(err, "decode")
+	}
+	return nil
+}