feature(validation): add data validation for valid/well-formed xml and json

...ko/fitconnect/api/exceptions/DataNotPresentException.java

...fitconnect/api/services/validation/ValidationService.java

.../fitconnect/core/validation/DefaultValidationService.java

...connect/core/validation/DefaultValidationServiceTest.java

core/src/test/resources/invalid_json_data.json

core/src/test/resources/invalid_xml_data.xml

core/src/test/resources/valid_json_data.json

core/src/test/resources/valid_xml_data.xml