Merge branch 'f-grpc-main' into f-grpc-f-acm

.../org/caosdb/server/transaction/DeleteUserTransaction.java

...aosdb/server/transaction/FileStorageConsistencyCheck.java

src/main/java/org/caosdb/server/transaction/Transaction.java

src/main/java/org/caosdb/server/utils/ServerMessages.java

src/main/python/grpc-prototype-client/EntityService.proto

src/main/python/grpc-prototype-client/EntityService_pb2.py

...in/python/grpc-prototype-client/EntityService_pb2_grpc.py

src/main/python/grpc-prototype-client/minimal_client.py