OVT-7653: First draft for validator interface

Intention is to validate arguments passed to REST-methods
OVT-7653: Fix typo
OVT-7653: Removed @PreAuthorize from GET methods

GET methods should be available without authentication
Merge branch 'develop' into error
OVT.7653: Utility class for checking common arguments
OVT-7653: Remove unnecessary throw declaration
OVT-7653: Validator for KoodistoDto

Validates cases when creating new Koodisto.
OVT-7653: Some null checks with tests
OVT-7653: Check for organization

And do not check for codesUri when validating creation, it is generated
from name.
OVT-7653: Use StringUtils instead of Strings
OVT-7653: Some additional utility checks

New methods throw given RuntimeException
OVT-7653: Additional checks and refactoring
OVT-7653: Validations for get and delete

Validations for get and delete arguments for codes with some
refactoring.
OVT-7653: Validation for inserting codeElement
OVT-7653: Validation for updating code element
OVT-7653: Validation for delete and fetch for code element
OTV-7653: Validates CodeGroup
OVT-8189: Added test for levels with relation.
OVT-8189: Removed the problem with duplicate levelswith-relation when codes has a relation to self.
OVT-8189: Fixing previous mistakes.