New Feature: Default Behavior Modification

* All: Supported the feature to set default behavior.
* NuGet: Modifying stub settings became a bit easier. The PowerShell command `Get-IndirectionStubSetting` supports generating unique name at the same time.
* NuGet: The classes which users unneeded were listed in the Intellisense, so applied the attribute EditorBrowsable with EditorBrowsableState.Never.
* Framework: About `IndirectionAssemblyRepository`, implemented the procedure to find indirection assemblies officially. In addition, made its methods virtual to isolate from its dependencies in the automated test.