Implement APIs for multiuser WifiEntries

This CL implements the stubs added for multiuser WifiEntries
- WifiEntry#isOwnedByCurrentUser
- WifiEntry#isSharedWithOtherUsers
- WifiEntry#setSharedWithOtherUsers
- WifiEntry#isModifiableByOtherUsers
- WifiEntry#setModifiableByOtherUsers

Flag: com.android.wifi.flags.multi_user_wifi_enhancement

Bug: 416638579
Test: atest WifiTrackerLibTests
Change-Id: I93c0cee840cad21f709ed7f1c48b05206e174fbb
5 files changed