wifi: wait for the framework to be ready before checking features

supplicant vts will stop and then start the framework, it is too
slow to allow next test checking necessary features.

This change also create a base class, SupplicantHidlTestBase, to do the
common initialization for all vts tests.

Bug: 167230822
Test: atest VtsHalWifiSupplicantV1_0TargetTest \
            VtsHalWifiSupplicantP2pV1_0TargetTest \
            VtsHalWifiSupplicantV1_1TargetTest \
            VtsHalWifiSupplicantV1_2TargetTest \
            VtsHalWifiSupplicantP2pV1_2TargetTest \
            VtsHalWifiSupplicantV1_3TargetTest \
Change-Id: Ice25c6d2198f719fc964a17515e66146a0a8ace2