* Update 23/24 lettings prepare your file guidance
* Separate and update bulk upload sales guidance
* Update shared guidance and sales file path
* Rename old_template_path to legacy_template_path
* Remove wrong bullet point
* Update legacy template path based on year
# Context
- https://digital.dclg.gov.uk/jira/browse/CLDC-2201
- Add copy to explain that the `username` field in new core accepts an email which differs from old core
# Changes
- Add copy to lettings and sales `Prepare your file` pages
* feat: add inset text and old template (actual link to come)
* feat: add old spec work from CLDC-1788 to avoid future conflicts, typo fix
* feat: add new files and update copy
* feat: add 23/24 spec files and update copy
* feat: specify rack version
* feat: specify rack version
* refactor: lint
* refactor: lint
* feat: fix failing tests
* db: update
* refactor: typos
* feat: update designs and add inset text
* feat: pass year to guidance page
* feat: merge with new behaviour on main
* feat: add new guidance page with corresponding template links for sales and lettings log
* feat: add specification files and links for sales/lettings
* refactor: tidying
* feat: change pseudo csv to xlsx to reflect reality
* feat: add tests for guidance page routing and content
* feat: add tests for lettings too
* add start of bulk upload logs journey
* split upload controller into 2
* add year page to bulk upload journey
* bulk upload years now dynamic
* add placeholder for upload your file page
* handle bulk upload when not in crossover
* add bulk upload csv user journey
* bulk upload now persists and sends to S3
* swap ruby-filemagic for file command
* match csv or text file for validation
* in_crossover_period? now uses overlap of forms
- also moved from Form to FormHandler
* add production env var for CSV bucket
* stub kernel call methods
* remove duplicate env var
* hardcode env var for review apps
* move feature toggle to FeatureToggle
* crossover period checks now specific to the form
* fix typo in bulk upload journey
* add start of bulk upload logs journey
* split upload controller into 2
* add year page to bulk upload journey
* bulk upload years now dynamic
* bulk upload journey: add copy for prepare file
* add link to bulk upload template
* add placeholder for upload your file page
* handle bulk upload when not in crossover
* fix tests around bulk upload redirect
* fix typos in bulk upload jouney