refactor: change RawContentKey to alloy_primites::Bytes - #1431

This is a good start, but I think that this PR should also make some changes in OverlayContentKey.

Here are the changes that we should do:

• remove Into<Vec<u8>> from supertraits set (we should use to_bytes directly)
• change TryFrom<Vec<u8>, Error = ContentKeyError> to TryFrom<RawContentKey, Error = ContentKeyError> in supertraits set
• to_bytes function should return RawContentKey

I think some of these are trivial, but some might require refactoring (I don't know until I try). If refactoring is not huge, I would put it into this PR, otherwise, it would be fine to split it into multiple PRs.

Few comments, repeating in many places:

• we should use RawContentKey::_ instead of Bytes::_ (example: Bytes::new())
  • this allows it easier to later replace RawContentKey with something else (instead of being alias) if we want to
  • it also makes code more explicit
• we should avoid unnecessary creating new objects, examples:
  • use RawContentKey::from_str directly (instead of using hex_decode to get Vec<u8> and then convert that into RawContentKey)
  • remove .clone() when not needed).

Looks good! If you can address last 2 comments, and I will merge the PR.