Enhancement: Provide Ruby binding impls

[enebo]

java_import Java::javafx.beans.binding.StringBinding

class RubyStringBinding < StringBinding
 def initialize(property:, method:)
 super()
 @property, @method = property, method
 bind @property
 end

 def computeValue
 property_value = @property.get
 return unless property_value
 property_value.__send__ @method
 end
end

The Java bindings provided from Bindings assumes Java reflective lookup so they cannot see our Ruby methods...

[enebo]

I should also point out that StringBinding is just some convenience methods on a type-erased type.

abstract StringBinding implements Binding<String>

so I think we can make a single binding to rule them all but we might not be able to leverage one of their abstract classes (unsure about that).