Rename AttributeDictionary to AttributeValueDictionary

[JeremyCaney]

There is already a class named AttributeDictionary in Microsoft.AspNetCore.Mvc.ViewFeatures namespace (reference). Unfortunately, the ViewFeatures namespace is often appropriate to introduce as a global namespace for view models. That introduces a naming conflict in the exact domain we expect to be using our AttributeDictionary.

The AttributeDictionary naming convention makes perfect sense for our needs. But to disambiguate it, we may want to rename it to AttributeValueDictionary. This isn't ideal, as it's inconsistent with most other attribute-related naming conventions in OnTopic as well as dictionary names in .NET. That said, there is at least some precedence for this in the ASP.NET Core MVC RouteValueDictionary, which is a mapping of route parameter names to route parameter values. That's not especially convincing, but as a popular class it at least provides some familiarity or justification for this convention, instead of it being entirely arbitrary.

Originally posted by @JeremyCaney in #99 (comment)

[JeremyCaney]

This was resolved in 0b62fe0.

[JeremyCaney]

This appears to be based on either an outdated issue or a faulty initial analysis.

If I recall, the initial issue was relevant to cshtml files, which rely heavily on classes in the ViewFeatures namespace (as the name suggests), and thus rely on that namespace being in scope. That said, the OnTopic.Attributes namespace is rarely needed in cshtml files since it pertains to the entity. And while AttributeDictionary is used by view models, it is exclusively used as a piece of scaffolding for the ITopicMappingService, and isn't publicly exposed via the view models, or accessed via the views. As a result, the scenarios where the two AttributeDictionary classes are used in the same context should be incredibly rare. (It does happen, but mostly when intercepting the view logic, as is done via TopicViewResult and TopicViewResultExecutor—which is a backend implementation detail, and not a common scenario for implementations).

It is conceivable that something has changed in how the .NET SDK handles global using directives with ASP.NET Core applications, thus resolving conflicts that previously existed (e.g., by exposing global using directives to cshtml files). That said, this isn't confirmed.

Regardless, this conflict doesn't appear to be an issue, and thus we should revert this work, preferring AttributeDictionary to AttributeValueDictionary. This has been done on the OnTopic Library (c0152cc) and the OnTopic Editor (be0b76c).