Firewall refactor identifiers

[allmightyspiff]

I don't like having to put in a differentiator for multiVlan and singleServer firewalls when interacting with a single firewall.

This might be a good candidate to try using the Search service for (#1815)
Or just try singleServer and if that 404s, try multiVlan, and if that 404s we know it doesn't exist.

Should effect the following commands

• slcli firewall cancel
• slcli firewall edit
• slcli firewall detail
• slcli firewall monitoring