Conform SignedDataVerifier & ChainVerifier to Sendable

[StefanPrintezis]

Summary

This PR improves thread safety and concurrency support by making SignedDataVerifier and ChainVerifier conform to the Sendable protocol. The main change involves replacing a mutable var for certificate caching with a dedicated CacheManager actor to ensure thread-safe certificate caching operations.

Changes

Core Changes

• SignedDataVerifier: Added Sendable conformance to enable safe concurrent usage
• ChainVerifier:
  • Added Sendable conformance
  • Replaced mutable verifiedPublicKeyCache with a dedicated CacheManager actor
  • Moved caching logic to the new CacheManager actor for thread safety

🆕 New Components

• CacheManager actor: A thread-safe actor that manages certificate verification result caching
  • Implements automatic cache expiration (15 minutes)
  • Handles cache size management (max 32 entries)
  • Provides thread-safe getCachedResult and cacheResult methods

🔄 Updated Types

• CacheKey: Added Sendable conformance
• CacheValue: Added Sendable conformance

🧪 Testing

• New test file: CacheManagerTests.swift with comprehensive tests for:
  • Cache storage and retrieval
  • Cache expiration behavior
  • Cache eviction when full
• Updated tests: Refactored SignedDataVerifierTests.swift to use the new caching architecture
  • Removed custom DateOverrideChainVerifier class
  • Simplified caching tests to focus on actual behavior verification

Benefits

1. Thread Safety: The CacheManager actor ensures all cache operations are thread-safe
2. Concurrency Support: Both verifiers can now be safely used in concurrent contexts
3. Better Architecture: Separation of concerns with dedicated caching logic
4. Maintainability: Cleaner, more focused test code

Breaking Changes

None - this is a backward-compatible improvement that enhances thread safety without changing the public API.

[StefanPrintezis]

PR Builder failed on missing gpg data? Doesn't seem related to the PR, can we try running it again?