wpa_supplicant: HIDL implementation (2/2)

Migrated the AIDL interface to HIDL.

Summary of the changes:
1. Changed method signatures to always invoke a callback with the
status of the operation and possibly a return value.
2. Use hidl_vec, hidl_string, hidl_array in place of
std::vector, std::string, normal array,  for all HIDL method params.
3. Removed all parcelables and instead use the structs declared in the
HIDL interface.
4. Moved all constants to enums and use static_cast to retrieve their
underlying values.
5. Changed the input params for |ISupplicant.createInterface|. Only the
interface name is passed by the caller, the rest of the params are
hardcoded in the implementation of the HIDL interface.
6. Changed any remaining comments from "C" style to "C++" style.
7. Move the implementation to
android::hardware::wifi:supplicant::V1_0::implementation namespace.

TODO's:
1. Need to handle the |notifyNetworkRequest|. This needs some
additional string parsing logic which will be handled in a future CL.
2. Death notifications are not yet added in the HIDL interface. So, that
part of the code is under "#if 0".
3. The |hidl_vec| implementation does not support an |assign| method
yet, so marked places where we need this for cleanup later.

Bug: 31365276
Test: mmm -j32 external/wpa_supplicant_8
Test: Will test on device using go/aog/279621 once the HIDL changes are
in AOSP.

Change-Id: Iff20fb3c6fc23b0122c0c07529171e3a473b1d63
14 files changed