WifiConfigStoreNew: Handle file not found

Since we might have genuine cases where the config store file is not
found (on a fresh install, user switch), handle the file not found
exception in |StoreFile.readRawData|.
|WifiConfigStoreData.parseRawData| can already handle null bytes passed
into it.

BUG: 29179579
TEST: Unit-tests

Change-Id: I0c6d79cd9752e6662d499b877879b8858e018dbd
3 files changed
tree: bfeecebe74b000ca49b7b45ed5d30af55e0c260a
  1. libwifi_hal/
  2. libwifi_system/
  3. service/
  4. tests/