Add rankingScores and badges to WifiPicker.

Adds support to request scores in WifiTracker and then plumb
those scores via AccessPoint.java. AccessPoints will sort on
ranking scores. Show badging in WifiSettings picker.

Bug: 33457699, 33778046
Test: Unit tests
Change-Id: Icc3161cf147b3a9715d6e9f56af574e52ae6c832