Measure and store some stats about blocks (see BlockStats), and write them to the DB.
num_inputs includes coinbase "inputs", but if a user only wants the non-coinbase inputs, they can simply subtract 1.
We separate the sum of the output sats into sum_coinbase_output_sats and sum_normal_output_sats, if someone wants the total output sats of the block, they can simply add them together.