Review classification of Kotlin standard libraries' methods as Assertions

[DavidRFerreira]

Issue:
Currently, besides including Kotlin's assert() method in the Assertions category, we also include the require(), requireNotNull(), check(), and checkNotNull() in this category.

Still, these four methods are different than an assertion. The methods return an IllegalStateException or an IllegalArgumentException instead of an AssertionError.

Another difference is that those four methods can not be disabled through the -ea JVM option like an assertion.

Goal:
Review the classification of those four methods - require(), requireNotNull(), check(), and checkNotNull() - as Assertions. Currently, it may be wrongly classified.