Server-Sent Event to get the players in the game

[smileydts]

@djpace14

Here's how you can test this branch to stream the current list of players to someone currently in the game:

1. Checkout branch of this pull request
2. Go to postman.com
3. Import the Postman collection from server\postman_collections\dog.postman_collection.json (use the import button on the screen)
4. docker-compose up
5. In another browser tab, navigate to localhost:5173 and join the game
6. In a new browser tab, navigate to http://localhost:5000/stream?player_id=0
7. In postman, run one of the API calls for another player to join the game
8. Go back to the browser tab where you entered http://localhost:5000/stream?player_id=0
9. You should see data returned with both players now in the game
10. Again using Postman, have two more players join the game
11. Each time a player joins, observe the data being sent in that tab with the stream. Once the game is full, each player should have cards.

[smileydts]

Superseded by dog-33-integrate-sse