Accepts the certificate from a heartbeat and stores its path in
driver_internal_info for further usage by the agent client (or
any 3rd party deploy implementations).
Similarly to agent_url, the certificate is protected from further
changes (unless the local copy does not exist) and is removed
on reboot or tear down (unless fast-tracking).
Change-Id: I81b326116e62cd86ad22b533f55d061e5ed53e96
Story: #2007214
Task: #40603