feat: Decouple asset_handlers into c2pa-codecs crate

[ok-nick]

Changes in this pull request

Decouples asset_handler/asset_io into its own crate.

Changes

• Separate/group encoding and decoding
  • Introduces Encode/Decode trait with the following methods:
    • Encode: write_c2pa, remove_c2pa, patch_c2pa, write_xmp, write_xmp_provenance, remove_xmp, remove_xmp_provenance
    • Decode: read_c2pa, read_xmp, read_xmp_provenance
  • Asset handlers (codecs) now take a read-only stream on construction
    • When signing, the typical workflow is read->write->read->write, there's a lot we can cache
  • Streams are no longer trait objects and instead generics (less overhead)
• Decouple hashers to the parsers
  • Introduces a Hash trait with 5 methods: hash, data_hash, box_hash, bmff_hash, collection_hash
  • Parsers can choose their default hasher (usually defined by spec) with Hasher::hash whilst also implementing any other supported hashes
  • Data hash now returns a list of byte spans corresponding to the manifest rather than explicitly defining byte ranges over the entire file
• Add file signature inference
  • Introduces a Supporter trait with 3 methods: supports_signature, supports_extension, supports_mime.
• Add Embed trait (composed manifests)
  • Construct an Embeddable with embeddable, read it from a stream with read_embeddable and write it to a stream with write_embeddable
• Codec is the new entry-point for asset handlers
  • It implements all traits and forwards it to the corresponding codec based on the file type
  • It is an enum over all codecs, removing the need for boxing trait objects
  • For instance, Codec::from_stream(&mut stream).read_c2pa()
• Granular parsing errors
  • It's now clear specifically where parsing went wrong, rather than "not found"
• Codecs are individually locked behind feature flags
  • If you only want png, enable the png feature, same with gif, jpeg, etc.
• External codecs
  • The Codec struct can be created with an external codec that implements the desired traits (user-defined codecs)
• Updated dependencies
  • Many parser dependencies have become unmaintained or deprecated

Testing

• Test the codecs separately from c2pa-rs
  • Use verified test image suites provided online, things like pngsuite, imagetestsuite, etc.
• Test all codecs simulatenously
  • Construct Codec and test read_xmp for all file types (no longer needs to be implemented for each asset handler)
• Fuzz the codecs
  • Individually fuzz each method of the codecs using afl or proptest

Related issues

• Separating Asset_IO to support third party contributions #398
• Read only mode for specific formats #381
• Duplication of code in store.rs with slightly different behaviors. #363

Checklist

• This PR represents a single feature, fix, or change.
• All applicable changes have been documented.
• Any TO DO items (or similar) have been entered as GitHub issues and the link to that issue has been included in a comment.