OGM-283 Add checkstyle rule: RedundantModifier

Checks for redundant modifiers in:

1. interface and annotation definitions,
2. the final modifier on methods of final classes, and
3. inner interface declarations that are declared as static

Rationale: The Java Language Specification strongly discourages the usage of "public" and "abstract" for method declarations in interface definitions as a matter of style.

Variables in interfaces and annotations are automatically public, static and final, so these modifiers are redundant as well.

As annotations are a form of interface, their fields are also automatically public, static and final just as their annotation fields are automatically public and abstract.

Final classes by definition can not be extended so the final modifier on the method of a final class is redundant.