WIP: entity-id

...end/implementation/MySQL/MySQLGetUpdateableChecksums.java

...se/backend/implementation/MySQL/MySQLSetFileChecksum.java

...osdb/server/database/exceptions/TransactionException.java

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

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

.../caosdb/server/entity/container/TransactionContainer.java

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

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

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

...rg/caosdb/server/resource/transaction/EntityResource.java

.../java/org/caosdb/server/transaction/WriteTransaction.java