Implement loading data directly as objects

What does this MR do?

This MR adds two features:

• During loading of data into attributes, can set unpack_data flag to directly store the object, not the container or group
• Add yaml_to_object load function

Can this MR be accepted?

• Implemented the changes
• Tests added or adjusted
• Pipeline passes
• Changelog entry added
• Version number bumped

Anything to double-check?

Nope.