Add days_left field

[TheAndrewJackson]

Purpose

Add dynamic days_left field that is generated based off of the current due_date value of a privacy request.

Changes

• Add new property to PrivacyRequest model
• Add new tests and update existing tests to work with new update

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 #1148

[TheAndrewJackson]

@sanders41 I updated the days_left field to use the property decorator and moved the function body inside the model. Since the function is inside the model now I left the parameter as self. If that doesn't make sense for the property decorator I can push up a quick update changing it

[sanders41]

The property update looks good. I'll approve and merge as soon as CI finishes.

[sanders41]

@TheAndrewJackson one thing I just realized, this updates a database model. Do we need a migration? Maybe not since it is just a property?

[TheAndrewJackson]

@sanders41 AFAIK we don't need a migration. We decided to calculate this property at the api level because it's a value that changes every day and there could be many changes if the org has a lot of privacy requests. It doesn't exist in the DB right now.

If at a later date we decided to move this property into the DB and have an automated job that updated all the due dates we would need a migration.