Revert "WifiConfigStore: Remove legacy modules"

This reverts commit a83bd15861ae7175b1f62bc2dc8de63e0dbe808e
and eventually support loading saved network creds from
wpa_supplicant.conf to WifiConfigStore.xml file.

CRs-Fixed: 2161641
Change-Id: Ic8222be386bc5064656b9df3f2f1a6af28de73b0
9 files changed