better handling of hex encoding

[bap2pecs]

if we have one key that's a byte array whose hex-encoded form is eacf2435ba6c2a29a58aba776e3cccbe7c54def6402518e63e9b3b042dbefcc4 and another key which is simply a string "eacf2435ba6c2a29a58aba776e3cccbe7c54def6402518e63e9b3b042dbefcc4", it will still display only one of them in the GUI

and this can lead to confusion b/c there are two data entries but we only show one

This already caused some trouble when we were debugging why FP daemon cannot start ("Err: cannot parse invalid wire-format data") even after we did the DB migration. it turned out that there is still a string key that we forgot to delete