Create lint rule to check order of data class methods

[dmdunla]

As of PR #444, we are planning to order the data class methods as follows:

1. slots
2. init
3. Property methods
4. classmethods (prefixed with @classmethod)
5. Public methods
6. Dunder methods (prefixed and suffixed with double underscores __)
7. Private methods (prefixed with an underscore _)

with alphabetical ordering within each section.

To check this, we should creating a linting rule to verify that the methods of the data classes follow this ordering.