feature(color-picker, time-picker): Provide mobile variant of picker popup

[motabass]

Right now using the pickers on small mobile devices can get cut off:

MatDatePicker solves this by using a centered popup for mobile devices

[jamesrusso]

I agree that simply centered would be the reasonable solution here and it should be possible to just use the underlying CDK overlay functionality "centerHorizontally" & "centerVertically" for certain viewport sizes maybe?

[motabass]

I did a workaround for now which prevents it from being cut-off but still does not center it:
2cda8bd