Adding feature flags

[MarcGuiselin]

The client takes way longer to compile than it should, and that's mostly because of the transient dependencies needed for the different integrations. We should spend time breaking down the client into individual feature flags that can be enabled when needed.

I'm not sure how best to do this. Someone with a more intimate knowledge of the dependency tree for the packages in this repo and how ipfs, fetch, eth, wrap-scan integrate into the client (or don't since I think wrap-scan is standalone though I'm not sure how that works).