Add pre-push lint?

[jacobheun]

Currently we don't do any pre-push behaviors in js-ipfs. Testing makes sense not to do because it takes way too long for everyone to have to run that locally. Linting is relatively quick (around 7 seconds for me locally).

While 7 seconds is annoying on a push, having this go to ci and doing an npm install on all agents before it lints is expensive if linting is going to fail, and is worth the time imo.

I think all warnings should be fixed before doing this.