Add static helper for creating static view models from bindings

[marner2]

WIP

• Adds a BindingT<'model,'msg,'a> type that mirrors Binding<'model,'msg> except it unboxes the output type (much more useful for static properties, not very useful for assembling into a list).
• Adds a static helper that can convert a string -> BindingT<'model,'msg,'a> to a property getter and setter.
  • Also maybe implement property getter and setter helpers for string -> Binding<'model,'msg>, which will not be nearly as type-safe since Binding<'model,'msg> doesn't carry type information for the property (boxes to obj)