Use main thread when creating internet signal icon

InternetTileDataInteractor would crash loading mobile icon because
SignalDrawable created a Handler() on a context that did not have a
looper assigned to it.

Flag: aconfig com.android.systemui.qs_new_tiles DEVELOPMENT
Fixes: 335868718
Test: atest InternetTileDataInteractorTest
Change-Id: I72439f72113cfd5c1e8d52dbd2d54b1c56951abd