[SB Refactor] Connect the old pipeline and new pipeline visibility

calculations together for wifi.

The _new_ pipeline has the source of truth for whether the wifi icon
*should* be visible. But, the _old_ view system has the source of truth
for whether the wifi icon *can* be visible (i.e. if there's enough
space for it).

This CL hooks up those two systems together by having
`WifiViewBinder#bind` return a `Binding` interface implementation,
similar to `KeyguardButtomAreaViewBinder#bind`. This allows them to
communicate with each other and correctly change the view's visibility.

Bug: 238425913
Test: manual: Go into airplane mode and verify that the wifi icon
disappears completely and there's no empty gap in the status bar.
Test: manual: Go into a state where there's not enough room for the wifi
icon and verify that just a tinted dot shows up. See demo video in
b/238425913#comment30.
Test: statusbar.pipeline tests

Change-Id: I9d421a4afb503c9327578f777561a4d38bf2fd48