BREAKING: Fix normalize for empty strings and 0 (#315)
This is breaking as it changes the behavior of the function with an empty string or 0 as input: it will now return 0x for an empty string and 0x00 for 0, instead of undefined
Fix issue introduced in v5.0.0 where the method encodeField encoded fields typed as bytes and passed as hexstrings were encoded differently than previous versions (#271, #274)