fixed readonly vars, refactored migrationService

...SchuhDemo/src/main/resources/schuh_vernichtung_spende.dmn

...mn/processfragmentation/BPMNVariableFormFieldScanner.java

...sis/Testgenerator/embeddedform/data/EmbeddedVariable.java

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

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

...muenster/masterthesis/Testgenerator/yaml/ActivityAdd.java

...nster/masterthesis/Testgenerator/yaml/ActivityDelete.java

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

...ster/masterthesis/Testgenerator/yaml/ProcessVariable.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