Refactored CodeGeneratorContext to CodeBuilderContext.

- Needed to separate the context's of "generation" and "building" to enable the communication of the TagHelperProvider.
Not sure I follow your numbering.

The goal is to communicate the ```RazorParser``` generated ```TagHelperProvider``` to the ```CodeBuilderContext``` that's used by the ```CSharpCodeBuilder``` to render ```TagHelper```s.