Nydus builtin P2P support

[imeoer]

Nydus currently supports P2P distribution of image blob data using dragonfly, but nydus and dragonfly are deployed separately, we need to deeply integrate with dragonfly to enable builtin P2P support.

[imeoer]

cc @Chenxi-Seu can help to do this, thanks!

[chenxi-seu]

I'll try my best to improve it.

[adamqqqplay]

@imeoer Due to lack of relevant progress, we may need to re-track this issue.