Add createSetLinkStateMessage method at RtNetlinkLinkMessage

This CL mainly adds the createSetLinkStateMessage() method at the
RtNetlinkLinkMessage class, that creates a link message to set the
interface up or down. The functionality is the same as
"ip link set $interface up" or "ip link set $interface down".

Bug: 364501824
Test: atest NetworkStaticLibTests

Change-Id: Id9232851f6d9a7f99f857fd5b8d4eae506de2c7c
4 files changed