659 Add Postgres and Redis to health endpoint

[eastandwestwind]

Purpose

Adds Postgres and Redis health checks to health endpoint.

Changes

• Return status of Postgres (including any migrations needed) and Redis to health endpoint
• Suppresses alembic and sqlalchemy logs for health endpoint

Checklist

• Update CHANGELOG.md file
  • Merge in main so the most recent CHANGELOG.md file is being appended to
  • Add description within the Unreleased section in an appropriate category. Add a new category from the list at the top of the file if the needed one isn't already there.
  • Add a link to this PR at the end of the description with the PR number as the text. example: #1
• Applicable documentation updated (guides, quickstart, postman collections, tutorial, fidesdemo, database diagram.
• If docs updated (select one):
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • documentation issue created (tag docs-team to complete issue separately)
• Good unit test/integration test coverage
• This PR contains a DB migration. If checked, the reviewer should confirm with the author that the down_revision correctly references the previous migration before merging
• The Run Unsafe PR Checks label has been applied, and checks have passed, if this PR touches any external services

Ticket

Fixes #659

[seanpreston]

It'd be great if we could change this response to "webserver": "healthy" to standardise the format across the services. Or alternatively something like:

{
  "healthy": True,
  "db": {
    "healthy": True
  },
  "cache": {
    "healthy": True
  }
}

[eastandwestwind]

good idea, I've updated to "webserver": "healthy"

[seanpreston]

Minor ask to standardise the formats in the response, aside from that this is great