Save some gas when looping over state arrays
There are a few loops over state arrays in `LiquidutyMining`.\\n```\\nfor (uint256 i = 0; i < leaderboard.length; i++) {\\n```\\n\\n```\\nfor (uint256 i = 0; i < topUsers.length; i++) {\\n```\\n\\nConsider caching the length in a local variable to reduce gas costs.\\nSimilar to\\n```\\nuint256 \\_usersNumber = allUsers.length;\\n```\\n\\n```\\nfor (uint256 i = 0; i < \\_usersNumber; i++) {\\n```\\n
Reduce gas cost by caching array state length in a local variable.
```\\nfor (uint256 i = 0; i < leaderboard.length; i++) {\\n```\\n