Enhance FirestoreOrganisationsRepository with team hierarchy management

- Introduced FirestoreTeamHierarchyRepository to manage team hierarchies within organisations.
- Updated create, getById, update, and delete methods to handle team hierarchy alongside organisations.
- Improved project management by associating projects directly with teams and ensuring proper hierarchy during updates and deletions.
- Refactored code for better readability and consistency, including standardized import statements.

Author: mrdavidlaing-mo