6233 migrate to schema rb

[ttoomey]

Merging this PR

• use a merge-commit or rebase strategy for PRs targeting the stable branch

Description

GH Issue

• use ruby to hold our db schema
• the fx gem supports triggers and functions
• the scenic gem (already in use) support views
• replace postgreSQL Rules with triggers/functions
• replace the deprecated rake 'db:structure' tasks with 'db:schema'

Type of change

Code clean-up

Checklist before requesting review

• I have performed a self-review of my code
• I have run the code that is being changed under ideal conditions, and it doesn't fail
• If adding a new endpoint / exposing data in a new way, I have:
  • ensured the API can't leak data from other data sources
  • ensured this does not introduce N+1s
  • ensured permissions and visibility checks are performed in the right places
• I have updated the documentation (or not applicable)
• I have added spec tests (or not applicable)
• I have provided testing instructions in this PR or the related issue (or not applicable)

//: # NOTE: system tests may fail if there is no branch on the hmis-frontend that matches the Source or Target branch of this PR. This is expected

[ttoomey]

per discussion with Elliot, I'll break this PR into smaller pieces that are easier to review:

• transition from rules to triggers
• fix the PK types in our dbs