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/crypto/encrypted_message.go

@@ -0,0 +1,57 @@
+package crypto
+
+import "go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+
+// EncryptedMessage of protocol.
+type EncryptedMessage struct {
+	AuthKeyID [8]byte
+	MsgKey    bin.Int128
+
+	EncryptedData []byte
+}
+
+// Decode implements bin.Decoder.
+func (e *EncryptedMessage) Decode(b *bin.Buffer) error {
+	if err := b.ConsumeN(e.AuthKeyID[:], 8); err != nil {
+		return err
+	}
+	{
+		v, err := b.Int128()
+		if err != nil {
+			return err
+		}
+		e.MsgKey = v
+	}
+	// Consuming the rest of the buffer.
+	e.EncryptedData = append(e.EncryptedData[:0], make([]byte, b.Len())...)
+	if err := b.ConsumeN(e.EncryptedData, b.Len()); err != nil {
+		return err
+	}
+	return nil
+}
+
+// DecodeWithoutCopy is like Decode, but EncryptedData references to given buffer instead of
+// copying.
+func (e *EncryptedMessage) DecodeWithoutCopy(b *bin.Buffer) error {
+	if err := b.ConsumeN(e.AuthKeyID[:], 8); err != nil {
+		return err
+	}
+	{
+		v, err := b.Int128()
+		if err != nil {
+			return err
+		}
+		e.MsgKey = v
+	}
+	// Consuming the rest of the buffer.
+	e.EncryptedData = b.Buf
+	return nil
+}
+
+// Encode implements bin.Encoder.
+func (e EncryptedMessage) Encode(b *bin.Buffer) error {
+	b.Put(e.AuthKeyID[:])
+	b.PutInt128(e.MsgKey)
+	b.Put(e.EncryptedData)
+	return nil
+}