Add ResponsiveContext

[ericsoderberghp]

Allow adding ResponsiveContext such that designs can show responsive behavior.

Have to think about what's the best way to represent this. One generally uses ResponsiveContext.Consumer to get the current breakpoint and then change the underlying layout and/or properties based on the breakpoint.

One idea would be to enable a breakpoint feature on any component. When enabled, it would allow the designer to customize properties and children based on breakpoint.