InSequence for protected mocks

[tonyhallett]

Will resolve #1173 when implementations are provided for two Setup methods as described below.

For discussion

There is common code with existing WhenPhrase and Mock methods that differ only in the condition - for instance

//When

		public ISetup<T> Setup(Expression<Action<T>> expression)
		{
			var setup = Mock.Setup(mock, expression, this.condition);
			return new VoidSetupPhrase<T>(setup);
		}
//Mock<T>

		public ISetup<T, TResult> Setup<TResult>(Expression<Func<T, TResult>> expression)
		{
			var setup = Mock.Setup(this, expression, null);
			return new NonVoidSetupPhrase<T, TResult>(setup);
		}

The code in this pull request follows suit. WhenPhraseProtected differs to ProtectedAsMock only by condition.

---

Note that WhenPhraseProtected throws NotImplementedException for SetupSet methods
These can be added to match #1165

[stakx]

@tonyhallett, same here as in your other PR, and as mentioned in the issue belonging to this PR: this isn't the right time to review code changes as long as no decision has been reached about the future direction for sequences. I'm not convinced at this time that the current .InSequence / MockSequence mechanism is the right way forward.