added gateway type, added gateway detection

...ster/masterthesis/Testgenerator/migration/ActionType.java

...asterthesis/Testgenerator/migration/MigrationService.java

...s/Testgenerator/rest/service/change/ChangeController.java

...erthesis/Testgenerator/rest/service/test/TestService.java

...e/fhmuenster/masterthesis/Testgenerator/yaml/Gateway.java

...enster/masterthesis/Testgenerator/yaml/GatewayAction.java

Testgenerator/src/main/resources/migration.yaml

...generator-web/src/app/components/test/test.component.html

...stgenerator-web/src/app/components/test/test.component.ts