TBE-44 Restructure the fyst test directories to clearly denote tax year and state

[mrotondo]

Link to pivotal/JIRA issue

• https://codeforamerica.atlassian.net/browse/TBE-44

PM Acceptance Required?

• No, this can be merged after code review acceptance

What was done?

• Moved the existing federal return XMLs into spec/fixtures/state_file/fed_return_xmls/{az, ny}
• Renamed them to remove fed_return_, _ny and _az
• Changed the implementation of the XMLReturnSampleService to load XMLs from the new directory structure into a hash structure that mirrors it
• Internal user-facing: Changed the implementation of StateFilePagesController (the list of fake returns to "transfer") so that it only shows returns from the current tax year and the selected state for the current intake
• Alternatives considered

How to test?

• Along with seeing automated tests pass, I manually verified the change to the fake returns page, and confirmed that they are still loaded correctly and that our stored federal submission IDs are loaded correctly when applicable
• All changes to the fake data transfer page can be viewed and tested on this PR's heroku instance
• Risk Assessment
  • We don't expose these returns externally, and aside from our automated tests, they are only used in the internal-only fake transfer page, so there should be no risk to this change

Screenshots (for visual changes)

• Before (showing the page for an AZ intake as an example, but NY would show both NY & AZ returns as well)

• After (showing the page for an AZ intake as an example, but NY would show only NY returns)

[github-actions]

Heroku app: https://gyr-review-app-4584-9d022c1e76c1.herokuapp.com/
View logs: heroku logs --app gyr-review-app-4584 (optionally add --tail)

[embarnard]

LGTM!