Consistent SA model setup

[MoralCode]

Description

• This change is a simple stylistic refactoring change that adjusts how our SQLAlchemy models are defined so that it follows consistent rules

These rules are:

• additional metadata parameters in models specifying constraints, tablename, or schema) appear at the top of the class definition
• these metadata definitions should use the simplest syntax available given what they need to do (i.e. if a model only needs a schema set, it can be defined as a plain dict, but if its a schema setting and constraints, it needs to be a tuple with the dict at the end)

This PR is intended to pull this relatively simple improvement out from #3435 to make that PR more easy to review.

Notes for Reviewers

This should be a relatively easy merge

Signed commits

• Yes, I signed my commits.

[sgoggins]

LGTM.