Make a uniform way of linter test implementation

[bdaase]

As a user, that wants to define customized linter tests, I would like to have a clear interface for linter test , I would like to add, to be able to add my own linting rules.
Therefore the test interface of the SwaLint-Plugins classes should be unified (the SmallLint test use a different way, then the other classes (they address RB classes)) and not need a registration of every part of the test.