Improve error message for large block timestamps

[fvictorio]

See #399

Instead of

data did not match any variant of untagged enum U64OrUsize at line 1 column 110

We should show a better error, something like Timestamp used for {method} is too large. Received {value}; the maximum value is {max_value}. (actual message tbd).

The affected methods are:

• evm_setNextBlockTimestamp
• evm_mine
• evm_increaseTime