WifiConfigManager: Separate validation criteria for update

For network config updates, the WifiConfiguration is expected to be a
sparse object with only the fields being updated being filled in. So,
separate out the network config validation criterions for the 2 cases.

Current special cases for update are:
1. SSID's are allowed to be null (because it may not be updated).
2. preSharedKey are allowed to be "*" (This is apps screwing up and sending
back the masked password back to us in an update).

Bug: 62955649
Test: Unit tests
Change-Id: I0c77af06503548f0887c41b02777f288f8a9d013
3 files changed
tree: 797a0b551f6ca5802ca7655df858e1309f507de0
  1. service/
  2. PREUPLOAD.cfg