slither-check-erc: detect if the token allows transfer to zero

If the token reverts when the value is zero, it might break third-party integration.

Additionally, several tokens require the approval to be zero before calling approve with a non-zero value, to prevent the ERC20 race condition. We could also report it.

It's probably worth to update our [token integration](https://github.com/crytic/building-secure-contracts/blob/master/development-guidelines/token_integration.md) checklist with these items