WIP: MAINT: refactor retrieve properties (move backend-logic to backend)

.../database/backend/implementation/MySQL/DatabaseUtils.java

...end/implementation/MySQL/MySQLInsertEntityProperties.java

...er/database/backend/implementation/MySQL/Replacement.java

src/main/java/org/caosdb/server/entity/Entity.java

src/main/java/org/caosdb/server/entity/EntityInterface.java

src/main/java/org/caosdb/server/entity/StatementStatus.java

...va/org/caosdb/server/entity/StatementStatusInterface.java

.../java/org/caosdb/server/entity/wrapper/EntityWrapper.java

...n/java/org/caosdb/server/grpc/CaosDBToGrpcConverters.java