[ipfs/go-bitswap] Bitswap Strategy Implementation

Hi!

Awhile back, I was working on an implementation of Bitswap strategies for my master's thesis. I took a break from the thesis, but am starting back to finish it in the Spring. I left off on a now outdated version of Bitswap (see https://github.com/dgrisham/go-bitswap, with my implementation specifically on the `impl/strategy-prq` branch). I've been passively watching the progress of this repo and noticed that a lot of improvements have been made, so I've been wondering -- is it in a solid/stable-enough state for me to re-implement strategies in the current version (with periodic rebasing on the changes to come, of course)?

Additionally, I want this update to be useful in actually implementing strategies into Bitswap if that's still one of the goals here. I'll be pretty tight on time with getting the thesis done, but I'd like to have open discussion on here as I do this implementation to get feedback from everyone as I go. I know this is mostly a matter of making a PR/issues and starting discussions, but just wanted to make a note in anticipation of those things.