Better detection of static IPs for DHCP server

Currently, AGH uses simple parsers for OS-specific network interface configuration files to detect whether or not an IP is static and other properties. But OS differ in what they support in these files and also there can be different ways to set up networking within a single OS (for example, Linux with its NetworkManager, networkd, etc.). We should at least attempt to get this information from the OS directly where it is supported.