Refactor Index Provider code

[gmelodie]

After the code in https://github.com/application-research/estuary/pull/159 is merged, we should spend some time refactoring the part copied from https://github.com/filecoin-project/index-provider so that it becomes more organized and clean. Also, we could contribute back to https://github.com/filecoin-project/index-provider with things that might not be relevant only to us.

[corinne-antonia]

@willscott Any thoughts here? Maybe we can brainstorm together what could come back to the index provider?

[willscott]

if you'd like to be able to more easily pull in upstream changes for efficiency that we're making to the library, you're welcome to let us know if there are other interfaces to index-provider you'd like us to maintain so you can use it directly.

[gmelodie]

I think the refactor here for us could have some important lessons to index-provider, but much of the work we'll do is to trim unused code and make it more specific for our use case.