Fix hex trace output

[ggwpez]

The trie trace logs use one line per byte, making it unreadable.
Instead put it in one line.

There is no test for this but I tested it in the playground.

[ggwpez]

It is still not really good readable, should I change it to hex::encode(…)?

[cheme]

It is still not really good readable, should I change it to hex::encode(…)?

Sounds good, maybe more ToHex as it is already use in the crate.