F multi retrieve

Summary

Implements multi-entity retrieval caosdb/customers/lfpb/management#393

See tests in caosdb-cppinttest!4 (merged)

Focus

• Most relevant changes are in include/caosdb/transaction.h and src/caosdb/transaction.cpp.
• New class MultiResultSet represents a result set with multiple entities. Is this a good name?
• New enum TransactionType restricts the kind of sub-transactions (Insert, Delete, Retrieve) which can be added to a transaction.
• Macros are used to check whether InsertEntity, DeleteById or RetrieveById can be called on a transaction (given the TransactionStatus and 'TransactionType`).

Test Environment

Test with server in branch f-grpc-f-multi-retrieve

Check List for the Author

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• 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?

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src/caosdb/configuration.cpp

@@ -35,15 +35,16 @@
 #include "caosdb/log_level.h"                          // for CAOSDB_DEFAULT...
 #include "caosdb/status_code.h"                        // for StatusCode
 #include "caosdb/utility.h"                            // for get_home_direc...
-#include <bits/exception.h>                            // for exception
 #include <cassert>                                     // for assert
 #include <cstdlib>                                     // for getenv
 #include <cstring>                                     // for strcmp
-#include <grpcpp/security/credentials.h>               // for SslCredentials
-#include <iterator>                                    // for next
-#include <map>                                         // for map
-#include <stdexcept>                                   // for out_of_range
-#include <string>                                      // for string, operator+
+#include <exception>                                   // IWYU pragma: keep
+// IWYU pragma: no_include <bits/exception.h>
+#include <grpcpp/security/credentials.h> // for SslCredentials
+#include <iterator>                      // for next
+#include <map>                           // for map
+#include <stdexcept>                     // for out_of_range
+#include <string>                        // for string, operator+
 
 namespace caosdb::configuration {
 using boost::filesystem::exists;