Enforce constrainedWidth in date and icons

That way, the views will properly adapt their content to the space
available. In particular, VariableDateView will choose the best format
to use based on space.

Test: atest CombinedShadeHeaderConstraintsTest
Test: manual using large screen size and text size
Bug: 258083936
Change-Id: Idae918ba27f143ce29ffa6ca3b865e77bbcecff1