Add unit tests for RancherHubConnector and various exporters

- Implemented tests for RancherHubConnector to validate fetching documents, handling errors, and managing state.
- Added tests for CsafExporter to ensure deterministic serialization of CSAF documents.
- Created tests for CycloneDX exporters and reconciler to verify correct handling of VEX claims and output structure.
- Developed OpenVEX exporter tests to confirm the generation of canonical OpenVEX documents and statement merging logic.
- Introduced Rust file caching and license scanning functionality, including a cache key structure and hash computation.
- Added sample Cargo.toml and LICENSE files for testing Rust license scanning functionality.

src/Scanner/__Libraries/StellaOps.Scanner.Analyzers.Lang.Rust/Internal/RustBinaryClassifier.cs

@@ -1,7 +1,7 @@
 using System.Buffers;
+using System.Collections.Concurrent;
 using System.Collections.Immutable;
 using System.Linq;
-using System.Security.Cryptography;
 using System.Text;
 
 namespace StellaOps.Scanner.Analyzers.Lang.Rust.Internal;
@@ -32,6 +32,8 @@ internal static class RustBinaryClassifier
         AttributesToSkip = FileAttributes.Device | FileAttributes.ReparsePoint,
     };
 
+    private static readonly ConcurrentDictionary<RustFileCacheKey, ImmutableArray<string>> CandidateCache = new();
+
     public static IReadOnlyList<RustBinaryInfo> Scan(string rootPath, CancellationToken cancellationToken)
     {
         if (string.IsNullOrWhiteSpace(rootPath))
@@ -49,7 +51,16 @@ internal static class RustBinaryClassifier
                 continue;
             }
 
-            var candidates = ExtractCrateNames(path, cancellationToken);
+            if (!RustFileCacheKey.TryCreate(path, out var key))
+            {
+                continue;
+            }
+
+            var candidates = CandidateCache.GetOrAdd(
+                key,
+                static (_, state) => ExtractCrateNames(state.Path, state.CancellationToken),
+                (Path: path, CancellationToken: cancellationToken));
+
             binaries.Add(new RustBinaryInfo(path, candidates));
         }
 
@@ -220,31 +231,13 @@ internal static class RustBinaryClassifier
 
 internal sealed record RustBinaryInfo(string AbsolutePath, ImmutableArray<string> CrateCandidates)
 {
-    private string? _sha256;
-
     public string ComputeSha256()
     {
-        if (_sha256 is not null)
+        if (RustFileHashCache.TryGetSha256(AbsolutePath, out var sha256) && !string.IsNullOrEmpty(sha256))
         {
-            return _sha256;
+            return sha256;
         }
 
-        try
-        {
-            using var stream = new FileStream(AbsolutePath, FileMode.Open, FileAccess.Read, FileShare.Read);
-            using var sha = SHA256.Create();
-            var hash = sha.ComputeHash(stream);
-            _sha256 = Convert.ToHexString(hash).ToLowerInvariant();
-        }
-        catch (IOException)
-        {
-            _sha256 = string.Empty;
-        }
-        catch (UnauthorizedAccessException)
-        {
-            _sha256 = string.Empty;
-        }
-
-        return _sha256 ?? string.Empty;
+        return string.Empty;
     }
 }