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.

include/caosdb/entity.h

@@ -367,7 +367,8 @@ public:
    * This is intended for debugging.
    */
   inline auto ToString() const -> const std::string {
-    google::protobuf::util::JsonOptions options;
+    google::protobuf::util::JsonPrintOptions options;
+    options.add_whitespace = true;
     std::string out;
     google::protobuf::util::MessageToJsonString(*(this->wrapped), &out, options);
     return out;
@@ -538,10 +539,10 @@ public:
    * This is intended for debugging
    */
   inline auto ToString() const -> const std::string {
-    google::protobuf::util::JsonOptions options;
+    google::protobuf::util::JsonPrintOptions options;
+    options.add_whitespace = true;
     std::string out;
     google::protobuf::util::MessageToJsonString(*(this->wrapped), &out, options);
-
     return out;
   }
 
@@ -649,7 +650,8 @@ public:
   [[nodiscard]] auto GetInfos() const -> const Messages & { return infos; }
 
   inline auto ToString() const -> const std::string {
-    google::protobuf::util::JsonOptions options;
+    google::protobuf::util::JsonPrintOptions options;
+    options.add_whitespace = true;
     std::string out;
     google::protobuf::util::MessageToJsonString(*(this->wrapped), &out, options);
     return out;