Built-in device uptime property using CLI-based parsing

NetBrain does not currently provide system uptime as a built-in device property. The existing workaround relies on an SNMP OID that uses a 32-bit tick counter, which resets after approximately 497 days and produces inaccurate results for devices with longer uptime. This enhancement would add device uptime as a native, built-in property populated through CLI-based parsing during discovery, rather than through a custom Qapp or SNMP polling. Customers with long-running network devices would gain accurate, out-of-the-box visibility into uptime without needing custom scripting or workarounds.