Lens Server's previously persisted state should be backed up before creating a new persisted state

As of now lens server state is persisted up every 5 mins . The sate is also persisted when server is going down.

Consider a scenario where server is running out of memory or all its threads are blocked and writes a corrupt state while going down. In this case we lose all the queries and/or session info.

Proposal : before creating a server state snapshot, the previous snapshot (folder) should be backed up. Now we will have two persisted states, the current one and backed up state(5 mins old state). If the current state is corrupt, server can use the backed up state in which case we lose out only on last 5 mins of state.