StatusBarDate: Add date on the status bar for the desktop experience

Add VariableDayDate to the status bar when
config_enableDesktopFeatureSet is enabled.

Also modify some bounds handling logic for this new added date view.

Bug: 378545144
Flag: com.android.systemui.status_bar_date
Test: ClockViewModelTest, ChipsMaxWidthTest,
StatusBarBoundsViewModelTest

Change-Id: I2f7b431b0104550ae56c1349ed9a072706c45d0c