Add deprecations to non-view WithViewStore initializers

[stephencelis]

We've found that WithViewStores overloads can really tax the compiler, so it's time to get prepare to remove them. The vast majority of uses are in SwiftUI views, so we can privilege the helper for that use case, and require a bit of extra work of manually observing a view store via @ObservedObject in the other cases.

In the future it would be nice to deprecate WithViewStore entirely, but we would want to offer a simpler tool, e.g. a property wrapper called @ObservedStore that smashes the concepts of Store and ViewStore together without a lot of boilerplate. This would lessen compiler strain by avoiding escaping closures and generic transforms in the view builder layer. Unfortunately, we still haven't figured out how to get property wrappers to work in a way that we find simple and intuitive.

In the meantime we can hopefully improve performance of the tool we provide by narrowing its focus to the most common builder.

[tgrapperon]

There are some tests in WithViewStoreAppTest that may already be removed I guess. There were only assessing that the overloads were effective.