Add progress log when starting nodeos with snapshot

[matthewdarwin]

When starting nodeos with a snapshot, it prints a line like this:

info  2021-07-12T14:31:04.177 nodeos    controller.cpp:541            startup              ] Starting initialization from snapshot, this may take a significant amount of time

Then for chains like wax, nothing is printed for several minutes.

It would be great to print a message once per second about the progress.