[Bug]: Autogen classes do not set required_name in fields

[rly]

What happened?

Similar to #798

When a group spec contains a subgroup, dataset, or link spec with a container data type, and the subspec has a name, the auto-generated class for that group spec should set "required_name": name for the corresponding subspec field in the class __fields__ variable. Currently, users can specify a different name for the subgroup/dataset/link object and add that object to the parent object without error. Writing the parent object will not write the child object, resulting in a file with missing data and possibly even an invalid file. This has caused problems with several extensions in the past, both for auto-generated classes and custom classes. For auto-generated classes, we can fix the custom class generator. For custom classes, we need to provide guidance in the documentation for writing extensions to avoid this gotcha.

Steps to Reproduce

n/a

Traceback

No response

Operating System

macOS

Python Executable

Conda

Python Version

3.11

Package Versions

No response

Code of Conduct

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• Have you checked the Contributing document?
• Have you ensured this bug was not already reported?

[rly]

Fixed by #800. I will open a separate ticket about improving the extensions documentation