Decorator type in documentation

[erik-brink]

What needs to be done:
Since the introduction of the check_mounted decorator, the generated documentation does not have proper documentation. The decorator "hides" its underlying method and its docstrings (for example, delete_folder has the type delete_folder(**kwargs: ~typing.~P) → T and no additional documentation)

Suggestions on how to get it done:

• https://stackoverflow.com/questions/3687046/python-sphinx-autodoc-and-decorated-members
• https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html#directive-automodule:~:text=It%E2%80%99s%20possible%20to,by%20a%20decorator.
• https://openmdao.org/newdocs/versions/latest/other_useful_docs/developer_docs/sphinx_decorators.html