Ability to copy a league from the previous season.

When copying we should be prompted for what additional parts should be copied.

1. Teams without the curlers attached, and renamed to "Team A", "Team B", etc.

2. Round robins.

3. Playoff brackets.

4. Draw schedule & games but with dates reflecting the new year. (need to account for leap years somehow) and the game results cleared.

Might obviate, or at least lower the priority of this feature: https://curling.canny.io/admin/board/clubs/p/round-robin-draw-generator