feat: implement support for JsonWebKey sets

[Stupremee]

Resolves #22

[Copilot]

Pull Request Overview

This PR adds support for JsonWebKey sets and enhances testing for JSON Web Signature functionality. Key changes include:

• Addition of new tests and functions to construct, sign, and verify using JsonWebKey sets.
• New methods in the JWS and JWK modules to work with multiple signers and verifiers via JsonWebKeySet.
• Updates to documentation and Cargo.toml to include the "crypto-rustcrypto" feature.

Reviewed Changes

Copilot reviewed 7 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/jws.rs	Added a new test case for signing JWS with JsonWebKey sets.
tests/jwk.rs	Introduced a new module to test the construction and retrieval of JsonWebKey sets.
src/jws/verify.rs	Added a new convenience method (verify_many_type) with enhanced documentation.
src/jws.rs	Added a new method (sign_many_type) for signing with multiple signers.
src/jwk/set.rs	New module providing the implementation for JsonWebKeySet management.
src/jwk.rs	Re-exported the new JsonWebKeySet for public consumption.
Cargo.toml	Updated default features to include "crypto-rustcrypto".

Files not reviewed (2)

• .nlsp-settings/rust_analyzer.json: Language not supported
• tests/keys/set.json: Language not supported

[codecov]

Codecov Report

❌ Patch coverage is 44.69697% with 73 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.3%. Comparing base (15abbd4) to head (b6ac756).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/jwk/set.rs	35.9%	73 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/jwk.rs	52.3% <ø> (+0.9%)	⬆️
src/jwk/policy.rs	38.0% <ø> (ø)
src/jws.rs	79.6% <100.0%> (+0.8%)	⬆️
src/jws/verify.rs	61.5% <100.0%> (+5.0%)	⬆️
src/jwk/set.rs	35.9% <35.9%> (ø)

... and 1 file with indirect coverage changes

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