Allow user to choose random seed incl. fallback in backend

[ndrsllwngr]

TODO

• fix error if "seed": null in backend and generate fallback random seed

POST /games
  Request Body: {"height":10,"width":10,"bombCount":20,"seed":null,"gameId":"noSeedProvidedByUser"}
  Accept: */*
  Status: 400 Bad Request 0.001915s

[ndrsllwngr]

@griase94 If you have time, I added a todo where in the code you could implement a fallback random seed generator.

[ndrsllwngr]

That was quick, nice @griase94

[griase94]

That was quick, nice @griase94

As call-a-pizza cartons say: "Kommt schnell, kommt gut"

[ndrsllwngr]

Haha @griase94 , I just tested it. Works fine. 💪