There are `Dp`, `DpOffset` and even `DpRect`, but ...

# compose

[orangy]

There are Dp, DpOffset and even DpRect, but no DpSize … For some reason, I need DpSize much more often than offset or rect. Could you please add it for completeness?

[orangy]

https://issuetracker.google.com/u/1/issues/194219828

[orangy]

@George Mount thanks for the change! I’d also add DpRect(DpOffset, DpSize) constructor function, and also add overloads with DpSize to Modifiers, like size, requiredSize. etc

[George Mount]

New CL is up for review.

[George Mount]

oh, that's a good idea for the modifiers. I'll do that, too.