DO NOT MERGE: Accomoditing API Review feedback for WifiScanner

cherry-picked from klp-wireless-dev
SHA1 8217e22356a8828a725ba7654cf25b05a49108fb

Main changes include

- hiding the API for LMP preview
- moved information elements to ScanResult object
- removed objects from events
- changed API names to be more consistent

Bug: 15191968
Change-Id: Ibe3907366aee85f7d56021a536ae0f9f9fb28b38