Data migrations for adding recruitment cycles to database

[elceebee]

Context

This PR follow on from this one. See that description for full context.

Changes proposed in this pull request

We add the dates to the database. Future PRs will use the dates.

• Using the database backed timetables for end of cycle related jobs
• Using the db backed timetables for UI conditions
• Using the db backed timetables for Cycle Switching (Ideally this will include an API end point for syncing with production)

Guidance to review

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist, if included inform data insights team of the changes
• If this code adds a column that may include PII, the sanitise.sql script and 0025-protecting-personal-data-in-production-dump.md ADR have been updated
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Attach the PR to the Trello card

[dcyoung-dev]

Small change suggested

[elceebee]

Add recruitment cycle data to database