GitLab

* refactor(tests): introduce testify

Introduce testify, cleanup lots of tests, add channel assertions to simplify channel tests, make
more readable

* refactor(tests): clean up error messages

* fix(deps): remove bitswap

remove accidentally added bitswap

* refactor(tests): put expected in correct position

Make sure for require.equal that the expected value is the first value

To reduce future import cycles, and expose more types properly, move the root package to an
interface/types file and move the main implementation into /impl. This also exposes an interface
other implementers can replace.

extracts parts of old asyncloader to load attempt queue
expands functionality of asyncloader to handle response cache
moves response cache and unverified block store under async laoder

Create a cache to manager how to track how long to keep unverified blocks around