Run an Erigon torrent tracker

This allows:

- monitoring torrent swarm health
- making changes to tracker behaviour without requiring client updates
- scaling to meet project requirements
- reducing dependence on third party trackers
- handling special cases around erigon torrents, like allowing peers to cross swarms and minimize announce overhead
- removing/simplifying tracker configuration which is currently duplicated in metainfos and magnet links, hardcoded in some parts of the code and otherwise inconsistent