WifiBackupRestore: Ignore non system created networks

Changes in the CL:
1. For new backup data, ignore networks non system app networks
during backup data generation.
2. For older wpa_supplicant.conf backup data, ignore non system
app networks during backup data restoration.

BUG: 29201888
Change-Id: Ie22a8f6d5eae03b01edf1420e2b8d3db5979449a
TEST: Unit tests
2 files changed
tree: 9e67ea5478ee5022aceb3322cc1bf30ae4bb7d04
  1. libwifi_hal/
  2. libwifi_system/
  3. service/
  4. tests/