Add lives system config

[jakubg1]

In gameplay.json, add a new lives section. Here are some example configs:

"lives": {
    "type": "none",
    "rollbackScoreAfterFailure": true
}

No lives system at all. The player has infinite attempts for any level.

"lives": {
    "type": "coins",
    "coinsForLife": 30,
    "rollbackScoreAfterFailure": false
}

Classic Luxor lives system.

"lives": {
    "type": "score",
    "scoreForLife": 50000,
    "countUnmultipliedScore": true,
    "rollbackScoreAfterFailure": false
}

Zuma-like lives system. The global score multiplier which would base on difficulty does not matter, even if not turned off by the score event.

Move this to difficulty configs once they're introduced.