Break out peertracker to its own library/repo under github.com/spiffe

[kfox1111]

As new agents using the Delegated Identity API come about, they need to have a way to track peers. The existing code for peer tracking in the SPIRE code base is useful for this purpose. It doesn't change much, so it shouldn't be very burdensome to break it out to its own library. Is this something we could do?

[evan2645]

spiffe/go-peertracker

SPIRE maintainers will maintain

[amartinezfayo]

I think that we need to ask the SSC to create the repository. @sorindumitru is also interested in having this in its own library and will be requesting the creation of the repo.

[kfox1111]

That is something I can probably do. Just a bare repo for now?

[amartinezfayo]

Sounds good!

[kfox1111]

Ok. Its created. I think you should have access to it? (https://github.com/spiffe/go-peertracker)