`neofs-lens storage inspect` unit test

[carpawell]

Is your feature request related to a problem? Please describe.

I'm always frustrated when a storage engine instance is up against some sensitive information that must not be changed, e.g. in the neofs-lens storage inspect command. Even if in RO mode.

Describe the solution you'd like

Add a unit test that ensures that an example storage has not changed after the command execution.

Describe alternatives you've considered

Have such a test in as an integrational one.

Additional context

https://github.com/nspcc-dev/neofs-node/pull/2543#discussion_r1315132559.