Support ICMP-Only Discovery and Live Access Mode

NetBrain currently expects devices to be reachable via SNMP or CLI to be fully onboarded and maintained in Live Access status, with ICMP-only reachability generally resulting in incomplete or excluded device records. This enhancement proposes a supported discovery and Live Access mode that allows devices to be discovered and tracked using ICMP (ping) only, without requiring SNMP or CLI credentials to establish a valid device record. Customers operating in environments where SNMP and CLI access are restricted or unavailable for certain devices would benefit from broader and more accurate network visibility, rather than having those devices excluded or misrepresented in the domain inventory.