Wifi: Clean up APIs

- Made WifiInfo.Builder public
- Made ScanResult::new public
- Added public getters for WifiNetworkSuggestion

Bug: 149912516
Test: compiles
Test: Will add CTS for new WifiNetworkSuggestion APIs
Change-Id: I868477f0d149cb4e96f9313dbaa1ef66d4723309
5 files changed