Have NewReadCloserWrapper pass through io.WriterTo
Have NewReadCloserWrapper pass through io.WriterTo

If the underlying io.Reader implements WriteTo, make
the wrapped ReadCloser implement it as well.

This causes the values returned by pkg/archive.DecompressStream
to implement WriteTo (for gzip and zstd, not bzip2 and xz),
and that in turn eliminates a 32kB memory allocation when
decompressing layers during pull.

Signed-off-by: Miloslav Trmač <9c008e38982a5397deb855345fb164f0558459ae@redhat.com>

containers/storage,containers/storage,containers/storage