Implement Big Data Service

[kalabukdima]

Right now we have a hotblocks service implemented in TypeScript, so it can't handle many clients.
The idea is to store the data from that service in a big OLTP database (probably Cassandra) so that any number of clients may query it with the same API.
This database may not only serve the latest data, but older data as well.

It may be treated as a centralized data lake that only serves full blocks but supports real-time data (incl. handling forks).