Update agent.go and handlers.go for 3rd party agent UI support

[0xTriboulet]

Fixed HealthUI and OS Version UI for 3rd party agents.

Havoc/teamserver/pkg/agent/agent.go

    // Updated OS Version handling - 0xtriboulet
    if val, ok := RegisterInfo["OS Version"]; ok {
        // Assuming val is a string representing the OS version, split it by '.' to get the version parts, 0xtriboulet
        versionParts := strings.Split(val.(string), ".")
        OsVersion := make([]int, len(versionParts))
        for i, part := range versionParts {
        OsVersion[i], _ = strconv.Atoi(part)
        }
        agent.Info.OSVersion = getWindowsVersionString(OsVersion)
    }

Havoc/teamserver/pkg/handlers/handlers.go

    // Update Callback time - 0xtriboulet
    if Teamserver.AgentExist(Header.AgentID) {
        Agent.UpdateLastCallback(Teamserver)
    }