EDELIVERY-2302 Refactored first 2 out of 3 deprecated classes

...src/test/java/eu/europa/ec/smp/api/GeneratedCodeTest.java

...in/java/eu/europa/ec/cipa/smp/server/security/Signer.java

...va/eu/europa/ec/cipa/smp/server/util/IdentifierUtils.java

...va/eu/europa/ec/cipa/smp/server/util/SignatureFilter.java

...opa/ec/edelivery/smp/services/ServiceMetadataService.java

...ropa/ec/edelivery/smp/services/ServiceMetadataSigner.java

...st/java/eu/europa/ec/cipa/smp/server/util/CommonUtil.java

.../eu/europa/ec/cipa/smp/server/util/DefaultHttpHeader.java

...u/europa/ec/cipa/smp/server/util/IdentifierUtilsTest.java

...ava/eu/europa/ec/cipa/smp/server/util/SMPDBUtilsTest.java

.../ec/edelivery/smp/services/ServiceMetadataSignerTest.java

...va/eu/europa/ec/edelivery/smp/config/SmpWebAppConfig.java

...pa/ec/edelivery/smp/validation/ServiceGroupValidator.java