R&D merge of explorer/consensus modules

[ ] layout on a high level how the merge would look like
[x] (phase 1) investigate if we can use an embedded DB which would require rich queries (queries that give freedom, on the fly, in what is to be computed and returned), GraphQL comes to mind;
- BoltDB can probably still be used for now, GraphQL will provide the API only:
  - [ ] An issue has been created for it: https://github.com/threefoldtech/rivine/issues/612
[ ] (phase 2) investigate if we want can'want-to use storm to enhance our boltDB usage: https://github.com/threefoldtech/rivine/issues/613
[ ] (phase 3) merge the two modules with a unified DB persistent backend
- ensure to have full compatibility with existing HTTP API Endpoints
- for the new queries new endpoints will be introduced
- this will be a breaking change in the Go Module API

Extra:

[ ] develop a small example frontend website that interacts with a local daemon and that showcases the richness of queries now possible

threefoldtecharchive / rivine