[GH-607] Only spawn bots if player is alive

[agustinesco]

Motivation

We were spawning bots that could move when a dead player leaves a match.

Closes #607

Summary of changes

• Now we'll only spawn bots if the player is alive, we're updating the enable field when a player dies so we'll use that

How to test it?

1. Change the players_needed_in_match variable to 3
2. Join a match with the browser client and the unity client
3. Die to the spawned bot in the unity client and leave the match
4. In main you'll see that the dead players is moving
5. In this branch that shouldn't happen

Checklist

• Tested the changes locally.
• Reviewed the changes on GitHub, line by line.
• This change requires new documentation.
  • Documentation has been added/updated.