ENH: Add datatypes and value classes to Extern C interface

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/420. Adapts the

Focus

The single get_value functions are now split up into get_<datatype>_value, get_value_list_length, and get_<datatype>_list_value_at functions. Also, importances, roles, and datatypes are now cast from string to enums and back for getting and setting. In the case of datatypes, two additional Booleans for is_reference and is_list.

In addition, the way memory si allocated in case of char pointers has been fixed.

Test Environment

Unit tests and integration tests should be sufficient. Integration testing with deploy in f-grpc and server in f-grpc-f-consolidation, as usual.

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.

test/test_ccaosdb.cpp

@@ -97,22 +97,18 @@ TEST_F(test_ccaosdb, test_execute_transaction) {
 }
 
 TEST_F(test_ccaosdb, test_multi_retrieve) {
-  std::cout << "Entering test_multi_retrieve ..." << std::endl;
   caosdb_connection_connection connection;
   caosdb_connection_connection_manager_get_connection(&connection, "local-caosdb-admin");
 
-  std::cout << "Creating transaction" << std::endl;
   caosdb_transaction_transaction multi_transaction;
   caosdb_connection_connection_create_transaction(&connection, &multi_transaction);
 
   // We explicitely want to define a C-style array here, so we disable
   // linting
   const char *ids[] = {"id1", "id2", "id3"}; // NOLINT
-  std::cout << "Adding mutli retrieval ..." << std::endl;
   int return_code(caosdb_transaction_transaction_retrieve_by_ids(&multi_transaction, ids, 3));
   EXPECT_EQ(return_code, caosdb::StatusCode::GO_ON);
 
-  std::cout << "Deleting transaction ..." << std::endl;
   return_code = caosdb_transaction_delete_transaction(&multi_transaction);
   EXPECT_EQ(return_code, 0);
 }
@@ -183,9 +179,7 @@ TEST_F(test_ccaosdb, test_entity) {
   return_code = caosdb_entity_entity_set_double_value(&entity, 5.0);
   EXPECT_EQ(return_code, 0);
   double value[] = {0.0}; // NOLINT
-  std::cout << *value << std::endl;
   return_code = caosdb_entity_entity_get_double_value(&entity, value);
-  std::cout << *value << std::endl;
   EXPECT_EQ(return_code, 0);
   EXPECT_EQ(*value, 5.0);
 
@@ -292,7 +286,6 @@ TEST_F(test_ccaosdb, test_list_property) {
 }
 
 TEST_F(test_ccaosdb, test_entity_with_parent_and_property) {
-  std::cout << "Creating objects ... " << std::endl;
   caosdb_entity_parent input_parent;
   int return_code(caosdb_entity_create_parent(&input_parent));
   EXPECT_EQ(return_code, 0);