F update

Summary

Implements update for a single entity

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/392

Focus

• Updating entities works like this: Retrieve an entity, copy it and put it in the update transaction.
• ResultSet has an iterator now
• I privatated SetId and SetVersionId (nobody should ever need to change it, because Entities which are to be updated have to be retrieved first anyway.)
• More fine-grained TransactionStatus (INITIAL -> GO_ON -> READY -> EXECUTE -> SUCCESS/ERROR) and corresponding StatusCodes

Test Environment

Use with server branch f-grpc-f-update

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

include/caosdb/status_code.h

@@ -24,6 +24,8 @@
 
 #include <string>
 
+namespace caosdb {
+
 /**
  * StatusCodes represent the status of this client, it's connections,
  * configuration and so on.
@@ -33,9 +35,6 @@
  * GENERIC_TRANSACTION_ERROR indicates that *there are* errors in a
  * transaction).
  */
-
-namespace caosdb {
-
 enum StatusCode {
   READY = -4,
   GO_ON = -3,