Exclude empty accounts and channels from sitemap.xml

[kontrollanten]

Describe the problem to be solved

In order to help search engines to prioritize content on Peertube sites we should exclude account and channels pages without videos nor playlists.

We've had a lot of issues with spam account which just creates accounts with a lot of links to different sites. Those pages should at least not be in the sitemap.

Describe the solution you would like

• Exclude [channel]/videos pages without videos.
• Exclude [channel]/playlists pages without playlists.
• Exclude account pages without videos.