Moving the wpa_supplicant interaction from the binder keystore service
to the new wifi keystore HAL.

Denials addressed:
03-29 00:04:52.075   734   734 E SELinux : avc:  denied  { get } for
pid=638 uid=1010 scontext=u:r:hal_wifi_keystore_default:s0
tcontext=u:r:keystore:s0 tclass=keystore_key

Bug: 34603782
Test: Able to connect to wifi passpoint networks. Denials no longer
seen.
Change-Id: I97eb9a4aa9968056a2f1fcc7ce5509ceb62fd41e