Show game code in host UI

**Is your feature request related to a problem? Please describe.**
Without the host having previous knowledge of game codes, there is no clear indication that they can be used to join a competition.

**Describe the solution you'd like**
The game code that players can use to join the competition, that will show a modal when clicked containing the following information: game code, ip address + port, and a brief textual overview about how the game codes work (basically just that they encode the ip address and port into the text)

Start by locating the host UI and the existing game-code join flow. Trace how competition details are displayed and how game codes are currently represented, then confirm the modal should show the game code, IP address and port, plus the stated explanation of encoding. Done means hosts can clearly open this information from the game code.

Written by the indexing model from the issue text.