Refactor/Modernize Entities and Controllers

[johnhenley]

Description of task

Wherever possible, refactor/modernize entities and controllers to use more modern DNN practices, such as DAL2, and modern C# features, such as generics.

• move entities to an Entities folder/namespace
• move controllers to Controllers folder/namespace
• mark old classes for future deprecation and use inheritance to handle any legacy consumers of a public method
• update existing code to use new classes

An example controller upgrade:

An example entity upgrade:

This issue is a placeholder/reference for related pull requests.

What general area(s)/component(s) are affected?

[] User interface
[X] Database schema
[X] Business Logic
[] Dependencies
[] Installation/manifest

[johnhenley]

All refactoring completed for 08.01.00 release; will open new issues for future releases