Extension API: Comments from API review council are addressed

Addressed all comments from API review council by renaming ScoreChangeCallback, the methods in ScoreChangeCallback, and the methods in WifiConnectedNetworkScorer.

Bug: 150878285
Bug: 135573686
Bug: 122133502

Test: atest android.net.wifi

Signed-off-by: Mingguang Xu <mingguangxu@google.com>
Change-Id: I823b52a95c2501c7431295573747f2228d1f50b0