`Pausable` can be more gas efficient using a similar mechanism as in the `ReentrancyGuard`

[eugenioclrc]

I noticed that the Pausable contract can be optimized for gas usage by adopting a similar mechanism used in the ReentrancyGuard contract.

💻 Environment

OpenZeppelin Contracts 4.9.3

📝 Details

The ReentrancyGuard contract uses uint256 constants to avoid the extra gas costs associated with boolean operations. This mechanism can be applied to the Pausable contract to make it more gas-efficient.

🔢 Code to reproduce bug