Add draggable content control

[jamesmcroft]

For those of you who may have ever worked with the original Surface (PixelSense), you may remember creating components that you could move around the screen. Here's an idea for everyone:

I've created a very, very basic control that can do the manipulation but wanted to gauge interest to see if it could be a useful control as part of the UWP community toolkit.

Here's a gif that I created of what my basic implementation does:

Thoughts?

[lukasf]

I don't have any use for this in an app right now, but I like it.

[deltakosh]

Per our discussion, closing it so far as we do not see a big ask on this control

[enghch]

I think this is a fantastic idea for a control. In #854 I described something very similar and gave several use cases where it would really help me.