New analyzer: Flag public methods in test classes that doesn't have a test attribute.

[Youssef1313]

xUnit

Whenever there is a class containing at least a method with [Fact] or [Theory], ensure all other public methods having one of these attributes.

MSTest

Analyze classes marked with [TestClass] and look for any missing [TestMethod] (or [DataSource]) on a public method.

NUnit

Analyze classes marked with [TestFixture] and look for any missing [Test] or [Theory].