Add equivalent Verifier

...e/unikoblenz/fgbks/base/utils/boundary/BoundaryUtils.java

...a/de/unikoblenz/fgbks/core/dmn/domain/vdmn/VDmnValue.java

...e/unikoblenz/fgbks/core/dmn/utils/DmnObjectContainer.java

...bks/core/dmn/verification/verifier/impl/DateVerifier.java

...e/dmn/verification/verifier/impl/EmptyOutputVerifier.java

...re/dmn/verification/verifier/impl/EquivalentVerifier.java

...ore/dmn/verification/verifier/impl/IdenticalVerifier.java

.../verification/verifier/impl/InputValueSyntaxVerifier.java

...fication/verifier/types/EquivalentStringVerification.java