implement operation auditing for minkube (--user) flag

[medyagh]

there should be a way to know what user did what operition on a minikube cluster

(to be used by multiple tools that use minikube at the same time
skaffold, cloud code, cloud run, cloud shel ....)

----------------------------------------
command, option, user , start_time , end_time
----------------------------------------
start, --driver=docker , driver, cloud-code, 223232,2 23232
start, --driver=hyperkit , driver, code-shell, 223232,2 23232
stop, steven, 223232,2 23232

if no user was provided, it should default to the OS user name

[spowelljr]

/assign

[priyawadhwa]

Ideas for this (no need to actually do them if you think of something better)

Commands we will track: start, stop, pause, unpause, delete
Command we won't track because they may clutter the log: status, version

Options for deleting the audit file:

1. consistently append to a single file and assume that it will be deleted whenever a user runs --purge
2. put a TTL on the audit file (if it hasn't been modified in a week, delete it and start a new one)

Whenever we append to the file, we can also log what we are appending to STDERR which will satisfy #9520