Update Bitstring Status List implementation.

[timothee-haudebourg]

This PR updates the Bitstring Status List implementation to the Candidate Recommendation Draft 10 June 2024. The current implementation is based on the Working Draft 6 April 2024.

In this new version, the statusSize, statusMessage and statusReference properties have been moved from BitstringStatusList to BitstringStatusListEntry. This has implications in the rest of the ssi-status crate. Because the status size is not stored in the list but in each entry, this changes the common API shared with TokenStatusList (defined in crates/status/src/impl/any.rs) so that a status size can be optionally passed to the access functions.

To accomodate status list construction I added the SizedBitString and SizedStatusList types that also store the status size.

There is still one small uncertainy about the new spec version because the old BitstringStatusList properties are still beeing referenced in one paragraph, but I think that's a mistake. Just to be sure I notified the vc-bitstring-status-list repo: w3c/vc-bitstring-status-list#175

Other changes

• Added the ssi-jws/secp256r1 for the ssi-status examples so that its able to verify the P-256 signatures given as samples.
• Added a signature to the status_list_revocable_*.jsonld sample files so the example client can verify them correctly.

[eelanagaraj]

some questions (mostly around the changes in spec & whether there are ways to mitigate some of the more problematic changes), but otherwise the changes themselves look generally good to me!

[eelanagaraj]

discussed with Timothée. Leaving the common interfaces as is for now as they are helpful for testing, and since the spec is not fully finalized yet anyways. Once it settles, the interface should be reworked in case there's a cleaner, more useful abstraction.