Send empty LinkProperties when entering StoppedState.

Additionally, no longer try to transition from within a State's
enter() method (this can encounter Log.wtf()s). Introduce some
CMD_JUMP_* commands and use deferMessage().

Test: as follows
    - built, flashed, booted
    - runtest -x IpClientTest passes
    - basic DHCP wifi association works
Bug: 69800563
Bug: 70394432
Bug: 80284937
Change-Id: I7ed6e1a994a3556af345e8a4dfb51c383f6d5478
(cherry picked from commit ffacb517d40df8ebb52d5906fa844b20c6520cd8)