[AWARE] Update network API: make open/encrypted explicit

Replace the older (implicitly) open network with 3 network
creation APIs:
- Open
- Passphrase-based
- PMK (SystemApi only)

Bug: 26564544
Bug: 35702875
Test: unit tests and integration (sl4a) tests
Change-Id: I29a1d668d245853755cd2dfaaa6c65fbb43989f7