Persist randomized MAC over forget network

Create and save a Map from configKey to the randomized MAC address for
each unique network ever created.

Bug: 122991465
Test: Unit tests
Test: Verified on device with MAC randomization on, add network, examine MAC address, forget network, add the same network again and verify the MAC address is the same as the previous one.
Change-Id: Ic703ec6fd3c9ccf36582b32721c0a4d703e66cc7
5 files changed