Let SNMP v3 User table can be updated

The Jira ticket is:

https://arraynetworks.atlassian.net/browse/TWSD-1531
The list is not clickable originally,

so I removed the code list_config_options={'click_enable':False}

then I set fields to be editable.

I also add _update for updating API.
The CLI is both for adding and updating.

Thus,

I add main operation function be called configure_user,

then changed _insert and _update function to call it.
You can see attachment for WebUI reference.