[SB Refactor] Implement the wifi icon flow in the new pipeline.

This also:
1) Makes the wifiNetwork flow a hot flow.
2) Makes WifiNetworkModel.Active a `data` class, which gives us much
   better logging for it.

**IMPORTANT**: I left two comments on this CL with details that are too
long for the CL description:
1) What business logic from the old code is being implemented in this
   new model
2) What implementation details are different between old and new

Test: statusbar.pipeline.wifi tests
Test: manual: See video attached to comment21 in bug
Bug: 238425913
Change-Id: I8ba985db575654c27587604b1858ec612dbf1423