Create a ServiceStatus Permanent Store

[AlfredoG87]

Persona

As a BlockNode Operator

Request

I want to be able to restart the BlockNode Server and the Servers state should be protected

Goal

So that BlockNode remembers what was the last_available_block after a restart.

Technical Notes

This interacts with #789 and should take that into account.
The idea here is to start with a very simple implementation that stores just enough data in the simplest useful format.
Later work will integrate the facility designed for #789.

[AlfredoG87]

No need to work on this anymore.