* new prometheus metrics for client-stats metrics
* adds client-stats types beacause they are
used by some of the prometheus collection code.
* new prometheus collector for db disk size
* new prometheus collector for web3 client
connection status
* adds client-stats api push cli in cmd/client-stats
* adds api metadata to client-stats collector posts
* appease deepsource
* mop up copypasta
* use prysm assert package for testing
