add missing tests from recent additions

[b5]

Test are are missing from recent additions:

• test getDagInfo hook on http via a 3rd requesting node
• test remove unpinning
• test remove hook
• Lots of attention is needed no the p2p side:
  • full hooks test suite
• setup codecov
  • run codecov tests with the race detector enabled

Finally, I've also seen some parallelism trip-ups that seems to stem from the timing around completion checks / final block not being added yet. This is mainly in the super-low-latency scenario of HTTP on the same computer. It'd be great to get a test that runs a 5-10 block dsync push any number of times checking for errors.