#2317353 Conditions tests refactoring

Ticket: 2317353 - RulesIntegrationTestBase + tests are using setContextValue() incorrectly

I have ported all the condition tests to the RulesIntegrationTest class and did some little refactorings around, such as separating Unit and Integration tests, renamed the base testcase classes to match PHPUnit's convention (*TestBase to *TestCase). I haven't looked at the Context Values yet as I am not sure if they have been fully fixed in Ticket 2346659.
This should mention the default is fine for modules below  core/modules.