Add static IpClient logging

Support keeping IpClient logs around and dumping them
during dumpsys.  Previously we got this benefit for
wifi by virtue of WifiStateMachine's long-lived nature.
Now that this is changing we need to be sure we have
logs, and this method gets us Ethernet logs as well.

Bug: 62476366
Bug: 77999594
Test: as follows
    - built
    - flashed
    - booted
    - runtest frameworks-net passes
    - dumpsys connmetrics [ipclient] works
Change-Id: I1136a83de8097fdb4130debe1eaf689be7132fe5