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_unpack.go

@@ -0,0 +1,71 @@
+package message
+
+import (
+	"context"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/message/peer"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+// AsInputPeer returns resolve result as InputPeerClass.
+func (b *RequestBuilder) AsInputPeer(ctx context.Context) (tg.InputPeerClass, error) {
+	return b.peer(ctx)
+}
+
+// AsInputUserClass returns resolve result as InputUserClass.
+func (b *RequestBuilder) AsInputUserClass(ctx context.Context) (tg.InputUserClass, error) {
+	p, err := b.peer(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	user, ok := peer.ToInputUser(p)
+	if !ok {
+		return nil, errors.Errorf("unexpected type %T", p)
+	}
+	return user, nil
+}
+
+// AsInputUser returns resolve result as InputUser.
+func (b *RequestBuilder) AsInputUser(ctx context.Context) (*tg.InputUser, error) {
+	user, err := b.AsInputUserClass(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	userID, ok := user.(*tg.InputUser)
+	if !ok {
+		return nil, errors.Errorf("unexpected type %T", user)
+	}
+	return userID, nil
+}
+
+// AsInputChannelClass returns resolve result as tg.NotEmptyInputChannel.
+func (b *RequestBuilder) AsInputChannelClass(ctx context.Context) (tg.InputChannelClass, error) {
+	p, err := b.peer(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	channel, ok := peer.ToInputChannel(p)
+	if !ok {
+		return nil, errors.Errorf("unexpected type %T", p)
+	}
+	return channel, nil
+}
+
+// AsInputChannel returns resolve result as InputChannel.
+func (b *RequestBuilder) AsInputChannel(ctx context.Context) (*tg.InputChannel, error) {
+	channel, err := b.AsInputChannelClass(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	channelID, ok := channel.(*tg.InputChannel)
+	if !ok {
+		return nil, errors.Errorf("unexpected type %T", channel)
+	}
+	return channelID, nil
+}