Improve analyzers for `[ClassInitialize]`, `[ClassCleanup]`, `[TestInitialize]` and `[TestCleanup]` to handle `[TestClass]` case

[Evangelink]

Unlike #3244 and #3245 when methods marked with the following attributes:

• [ClassInitialize]
• [ClassCleanup]
• [TestInitialize]
• [TestCleanup]

are on a class not marked with [TestClass] it's possible that they are still being picked-up through inheritance.

In addition to #3223 and #3224 updates, we should raise a diagnostic if the containing type is sealed and not marked with [TestClass] (or derived attribute).