[date-picker] focus state on calendar dropdown clashes with selected date

[dakahn]

Give the date picker component keyboard focus and hit the down arrow to open the calendar dropdown. Focus has moved to the dropdown component, but if there is a previously selected date visually the focus state is undetectable

The selected date and the currently focused date is 2/5

@snidersd tagging you here since you found this one

[aagonzales]

Good catch, for selected+focus lets treat it the same we do with our primary button, so it should get that 1px white inset border.