fix(RingBufferLib): improve lib

[PierrickGT]

Issues:

• https://linear.app/pooltogether/issue/POOL-1667/ringbufferlib-no-need-to-cast-cardinality
• https://linear.app/pooltogether/issue/POOL-1668/ringbufferlib-wrap-should-be-used-when-needed
• https://linear.app/pooltogether/issue/POOL-1676/ringbufferlib-offset-and-nextindex-should-be-documented
• https://linear.app/pooltogether/issue/POOL-1681/ringbufferlib-mostrecentindex-should-be-better-documented

[linear]

POOL-1667 RingBufferLib: no need to cast _cardinality

File: https://github.com/pooltogether/pooltogether-contract-tsunami/blob/3e535ef0acccd270324d47c22aa0215773173c25/contracts/libraries/RingBufferLib.sol#L36

In the **mostRecentIndex **function, we pass _cardinality as a uint256 and then we cast it again to uint256 in the return calculation. This is unneeded and can be remove like so:

return (_nextAvailableIndex + _cardinality - 1) % _cardinality;

We could also use the wrap function to handle this calculation:

return wrap(_nextAvailableIndex + _cardinality - 1, _cardinality);