feat: Crypt4GH support using LocalStorage

[mmalenic]

Changes

• Add Crypt4GH support for LocalStorage. The process is:
  • The server is configured with a private_key and recipient_public_key.
  • Encrypted files are decrypted by htsget-rs using the private_key.
  • Byte ranges are calculated on unencrypted data.
  • Byte ranges are converted to encrypted ranges, and the Crypt4GH headers are reencrypted and served to the client along with edit lists.
  • The client is expected to decrypt the resulting concatenated bytes using their private key, which corresponds to the recipient_public_key.
• Storage is significantly refactored, it now uses dynamic traits and some heap-allocated indirection. I think this was necesssary because otherwise there would be a large amount of less readable generic types on many structs in htsget-storage and htsget-search. This would be coupled with many more #[cfg(feature = "c4gh-experimental")] flags, and I thought it would be best to reduce these.
  • The C4GHStorage now wraps any other StorageTrait and decrypts the stream.

A lot of this code is copied from the existing https://github.com/umccr/htsget-rs/tree/crypt4gh branch, except it's been tidied up and made a bit more generic so that it supports other storage interfaces, not just UrlStorage.

I think a lot of the code under https://github.com/umccr/htsget-rs/blob/feat/crypt4gh-storage/htsget-storage/src/c4gh/edit.rs and https://github.com/umccr/htsget-rs/blob/feat/crypt4gh-storage/htsget-storage/src/c4gh/mod.rs belongs in the Crypt4GH-Rust repository eventually.

[brainstorm]

Shall we deprecated PR #223, @mmalenic ?

Answer IRL: No because NBIS depends on a few bits in there still.

[brainstorm]

A few bits to address after discussing IRL:

• S3 and URL storage support after this PR.
• Rename c4gh-experimental to just experimental as we can reuse it with out-of-spec features such as BED support in htsget.
• Drop object_type naming in favor of crypt4gh_keys (or similar) in the resolver configuration. Related to Crypt4GH secrets manager #264.
• README.md: Don't stop at samtools view output erroring on EOF, explain why it errors and show a solution for it?
• Document third party htsget python client support for crypt4gh.

[mmalenic]

#265 addresses point 2, and will allow the remaining points to be implemented in another PR.