v4: Static View Models

[marner2]

Here is a summary of the "Static View Models" feature being added to v4.

• Split apart BindingData and DynamicViewModel/Binding concepts
  • Remove dependency on ViewModel Class type in Binding Data. #449
  • Split binding helpers not related to ViewModel.fs after it #450
  • Split ViewModel.fs into DynamicViewModel.fs and BindingVmHelpers.fs #467
  • Minimize and types in binding vm helpers #468
  • Rename ViewModel<'model,'msg> to DynamicViewModel<'model,'msg> #469
  • Split binding apart from binding data #472
  • Split out bindingdata create functions #474
  • Move create and mapMinorType functions to Binding and Internal consistently #484
• Make so that types are more variant (use get/set instead of ref/mutable types)
  • Add SelectedItemBinding type instead of tuples #454
  • Add CollectionTarget so that SubModelSeq's can be properly typed #459
  • Change typed refs in VmBindings to getset #475
• Group related functionality more closely together
  • Add view model args and send them through Initialize and Update #451
  • Move ViewModelArgs into their own file #453
  • Add fakes for design time view model #460
  • Fix renaming issue with fake->none #461
  • Add ofNull and toNull to ValueOption #495
  • Move boxing out of BindingData #497
  • Refactor long line bindingvmhelpers #498
  • Remove dispatch from update #489
  • Move createBinding to Binding.fs since it isn't used anywhere else #506
• Add typed 'vm argument to BindingData so that the property can be statically typed
  • Strongly type Get and Set Binding Data #464
  • Add collection type bindings #505
  • Add test for binding vm helpers #504
  • Add output type information to BindingData #470
  • Box BindingData output type separate from minor types #512
  • Add output type parameter to BindingVmHelpers #511
  • Make WpfProgram more flexible #513
  • Make type of get/set propagate to static view model property #508

Remaining work (3-31-2023):

• Bring up to parity with version @marner2 is using
  1. Use maps instead of ireadonlydictionary #547
  2. Extract function into helper #548
  3. Add untyped base view model for static view models and example project #522
  4. Box BindingData output type separate from minor types #512
  5. Make type of get/set propagate to static view model property #508
  6. Make WpfProgram more flexible #513
  7. Make so elmish update and cmd loop can run on non-ui thread #552

And of course:

• Modify documentation to mention this method of construction.

There are fundamentally two parts to this push. The first is to allow statically-defined view model types to work with Elmish, and the second is to allow the properties of those view model types to be statically typed.

From a discussion with @TysonMN about the advantages of statically typed properties:

When used in the context of "dot" notation in the XAML project, you will be able to get compile-time help for things like ViewModelProp.SubModel.Prop. If those were constrained to obj, you wouldn't get compile-time checking of those types.
Also XAML will warn you about type issues (number vs string, etc)

In addition, allowing statically-defined view model types will enable users to call out these view model types by name. This will allow things like data templates with explicit DataTypes set.

[marner2]

#552 is technically beyond the scope of "Static View Models," which is now feature complete.

I think we're ready to add documentation for it. @LyndonGingerich if you're interested.

[marner2]

#520 this documentation can resume.

[marner2]

This is now completed