[NFCT.NS.8] Parse conntrack attribute CTA_STATUS and CTA_TIMEOUT

Parse CTA_STATUS and CTA_TIMEOUT for the IPv4 BPF tethering offload.
More attributes need to be parsed in the follow-up commits.

Test: atest TetheringCoverageTest
Change-Id: Ic2080d33d0517ef81ce92e189506fb1bb2425003
5 files changed