Refactor address crate

[austinabell]

Summary of changes
Changes introduced in this pull request:

• Refactors address to remove heap allocation and allows easier access to the underlying data
  • Can match on <Address>.protocol() to access the actual data format of the address, instead of retrieving the encoded bytes and do own validation with the protocol and decoding in some cases.
  • Mainly needed to retrieve the BLS public key from that address type when needed, instead of having to validate and copy to a buffer
  • Removes possible errors from instantiating anything except BLS Address type (This can be removed as well, but requires a [u8; 48] to be passed in instead of a slice, and this is not very ergonomic to use)
  • Allows addresses to implement Copy now

Interface should just be an extension of what exists now, except for the constructors, which are breaking changes

Reference issue to close (if applicable)

Closes

Other information and links

[dutterbutter]

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