* 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-2301
- Content for 2022 and 2023 bulk upload journey need to differ to give users the correct info they need to complete the journey
# Changes
- Update 2022 and 2023 `Prepare your file` and guidance pages
* 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