Head caching and health monitoring

[makemake-kbo]

Monitor the head of the chain, and have a live DB(hashmap that lives in memory?) that can be used to temporarily cache data at the head. The cached data could later be inserted into the historical data DB.

A prerequisite for this is RPC and chain health monitoring. RPC nodes should be removed from the rotation if they are erroring/falling behind. The chain needs to be monitored for reorgs if we are going to be inserting the live db into the historic one.

[makemake-kbo]

health monitoring works, need to implement head caching and reorg reverting

[makemake-kbo]

all done in head-cache