Give visibility to RFS and packages in need of a sponsor

There are currently RFS getting automatically closed due to a lack of sponsor.

This issue is opened to list possibles ways to give better visibility to packages in need of sponsor.

One of them could be to create a weekly reminder like wnpp's report on debian-devel@lists.d.o (example: https://lists.debian.org/debian-devel/2018/12/msg00356.html)

The report could list new opened RFS, prioritizing the one not owned (still in need of sponsor).