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/uploader/small.go

@@ -0,0 +1,66 @@
+package uploader
+
+import (
+	"context"
+	"io"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgerr"
+)
+
+func (u *Uploader) smallLoop(ctx context.Context, h io.Writer, upload *Upload) error {
+	buf := u.pool.GetSize(u.partSize)
+	defer u.pool.Put(buf)
+
+	last := false
+
+	r := io.TeeReader(upload.from, h)
+	for {
+		n, err := io.ReadFull(r, buf.Buf)
+		switch {
+		case errors.Is(err, io.ErrUnexpectedEOF):
+			last = true
+		case errors.Is(err, io.EOF):
+			return nil
+		case err != nil:
+			return errors.Wrap(err, "read source")
+		}
+		read := buf.Buf[:n]
+
+		// Upload loop.
+		for {
+			r, err := u.rpc.UploadSaveFilePart(ctx, &tg.UploadSaveFilePartRequest{
+				FileID:   upload.id,
+				FilePart: int(upload.sentParts.Load()) % partsLimit,
+				Bytes:    read,
+			})
+
+			if flood, err := tgerr.FloodWait(ctx, err); err != nil {
+				if flood {
+					continue
+				}
+				return errors.Wrap(err, "send upload RPC")
+			}
+
+			// If Telegram returned false, it seems save is not successful, so we retry to send.
+			if !r {
+				continue
+			}
+
+			break
+		}
+
+		upload.sentParts.Inc()
+		if err := u.callback(ctx, upload.confirmSmall(n)); err != nil {
+			return errors.Wrap(err, "progress callback")
+		}
+
+		if last {
+			break
+		}
+	}
+
+	return nil
+}