Send list of hidden networkID for supplicant scan

Since we disable all the networks in wpa_supplicant (as of b/26984166),
we need to explicitly send the list of hidden ssid's to scan.

1. Use the 'scan_id' override to send a lit of hidden networkId's to
supplicant.
2. Add a new set of hidden networkId's in ConfigurationMap which can be
used as parameter for the above.
3. Add a test to start scan with a hidden network added.

BUG: 27471630
TEST: Verfied that we auto-connect to a hidden ssid.
TEST: `runtest frameworks-wifi`

Change-Id: I8aea09d1ec2f24310959a558e8b12d31a26d179c
9 files changed
tree: 378dec1ae0c82d327a4b7573481f064c7ecc6d24
  1. service/
  2. tests/