Split binding helpers not related to ViewModel.fs after it

[marner2]

Moves all of the bindings helpers into a new file that has visibility into the ViewModel.fs file. The reason for this is twofold, one to split away everything that ViewModel.fs isn't dependent on, and another to allow future expansion of Bindings to have access to ViewModel.fs when we change things up.

#449

[TysonMN]

one to split away everything that ViewModel.fs isn't dependent on

I am satisfied with this first reason.

How about we call these files BindingsInternal.fs and BindingsPublic.fs? That accurately describes the difference between these files, right? If so, do you think will that continue to be an accurate description as you make all your desired changes?

[marner2]

Actually if I go Bindings.fs and BindingsInternal.fs it might shrink the diff significantly, hang on...

[marner2]

@TysonMN please review. There are no actual code changes, only rearrangements.