[WIFI] Fake Scan result via shell command

Add mechanism to fake scan results - allows testing of some aspects
of the framework or external components (e.g. Settings).

Bug: 188288389
Test: add fake scans, verify via Settings
Test: atest android.net.wifi
Test: atest com.android.server.wifi
Change-Id: I2b1fb89c9c598f157b58e9f11c93ab8bcef67e96
7 files changed