Add properties collection to more entities

[philipdanielhayton]

It'd be super useful if we could store additional properties against entities such as Payment Methods, Shipping Methods, and Stores, like how we do with Orders and Products. To my knowledge this isn't currently possible without rolling your own DB table or other solution.

One of our projects in particular has a lot of supplementary data for Shipping Methods that we've stored in the content tree but it would make sense for the editors to be able to change that right on the Shipping Method itself.