[ABO-225] Concurrent Seasons

[DidacSF]

Description

This PR changes the way seasons are started and finished, together with how we store the season state, in order to make it possible to have multiple seasons running at the same time.

Type of changes

• [ ] build: Changes that affect the build system or external dependencies (eg, Cargo, Docker)
• [ ] ci: Changes to CI configuration
• [ ] docs: Changes to documentation only
• [x] feat: Changes to add a new feature
• [ ] fix: Changes to fix a bug
• [x] refactor: Changes that do not alter functionality
• [ ] style: Changes to format the code
• [x] test: Changes to add missing tests or correct existing tests

Checklist

• [x] Tests for the changes have been added
• [x] Necessary documentation is added (if appropriate)
• [x] Formatted with cargo fmt --all
• [x] Linted with cargo clippy --all-features --all-targets
• [x] Tested with cargo test --workspace --all-features --all-targets