Randomize the local Wifi IPv4 address

Also: address a few "error prone" warnings, adding @Override where missing

Test: as follows
    - built, flashed, booted
    - wifi tethering uses a randomized address, DHCPv4 and DNS works
Bug: 32163131
Bug: 70673901

Merged-In: I47d75c32ccd4bcbbb2f05637fcbae216d7e15015
Merged-In: I8f8397978a13c8b2303dfcd950700b447ea61d3c

Change-Id: Icfabc48f2cf97b362ce292747f47021e84b900da