SpringBoot Move BindMethod to context.properties.bind and expose it on Bindable

To fix #35564, BindableRuntimeHintsRegistrar needs to know the binding method to be used in addition to the type that is to be bound. To this end, we'd like Bindable to expose a BindMethod but doing so at the moment will create a package tangle. To remove the tangle, BindMethod should move to the context.properties.bind package.