Params arg unit test

[Jason31569]

• Unit test for params arg as suggested Ability to mock protected methods with and without return value #845 (comment)
• Fix WhenCalled.cs indentation problem and removed unused using
• Fix RaiseEventHandler.cs indentation problem and removed unused using

[Jason31569]

@dtchepak can you review please? Adding suggested params arg unit test, also fixed some (pre-existing) formatting errors that were being flagged by new checks

[dtchepak]

LGTM! Thanks!