refactor: python models

[bryanchriswhite]

Rationale

1. Some inconsistencies have developed over time around the convention
2. The recent python linting PRs and resulting refactoring has illustrated the cost of unnecessary complexity in this area of the code

Changes

• rename python model classes to match their respective table names
  • table name is the lower snake case of the respective class name
  • clean up any inconsistencies
• compute table name in parent class using sub-class name
• remove (now redundant) get_table methods from NamedFields sub-classes

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Code Review Checklist (to be filled out by reviewer)

• [ ] Description accurately reflects what changes are being made.
• [ ] Either the PR references an issue (via the "Development" combobox) or the description explains the need for the changes.
• [ ] The PR appropriately sized.
• [ ] The PR contains an idempotent DB migration.
• [ ] I have verified the correctness of the DB migration using relevant data (e.g. test-generated data).
• [ ] New code has enough tests.
• [ ] New code has enough documentation to answer "how do I use it?" and "what does it do?".
• [ ] Existing documentation is up-to-date, if impacted.