Commented Task: Add Test Cases for All the current methods that does not [1785]

Possibility to Mock<IToken> to get the results we expect instead of directly performing the queries.
Comments: Associated with changeset 33781: Version 0.9.0.0
- Tested MessageQueryGenerator
- Added Id condition on CanMessageBeDestroyed
- Added UserQueryValidator
- Added checks for ScreenName
- Added check for MessageId parameter
- Updated tests to cope with new code logic for checks
- Added a TestHelper to simplify the creation of random id and string