Enforce that `dataHash` is the hash of `data`

[rmeissner]

It is not enforced that dataHash is the hash of data. It would make sense to add a require for this to avoid unexpected behaviour.

Reference: https://github.com/safe-global/safe-contracts/blob/3c3fc80f7f9aef1d39aaae2b53db5f4490051b0d/contracts/Safe.sol#L286-L316