Partial animation based on input value (for interactive, scrubbable animations)

[cleercode]

Based on knowing before and after properties (especially makes sense with states) and an input and its range of values (ex. a draggable layer's y position), it should be possible to set the layer's properties to an appropriately scaled in between state. This'd make it easy for users to set up interactive draggable transitions by just calling this function within a dragmove event. This is similar to what can be done manually with Utils.mapRange and I'm not sure what the right approach is for how much more this should be built into Framer, but it seems like it's a popular use case that could be made easier.