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/RustFingerprintScanner.cs

@@ -1,3 +1,4 @@
+using System.Collections.Concurrent;
 using System.Text.Json;
 
 namespace StellaOps.Scanner.Analyzers.Lang.Rust.Internal;
@@ -13,6 +14,7 @@ internal static class RustFingerprintScanner
     };
 
     private static readonly string FingerprintSegment = $"{Path.DirectorySeparatorChar}.fingerprint{Path.DirectorySeparatorChar}";
+    private static readonly ConcurrentDictionary<RustFileCacheKey, RustFingerprintRecord?> Cache = new();
 
     public static IReadOnlyList<RustFingerprintRecord> Scan(string rootPath, CancellationToken cancellationToken)
     {
@@ -31,7 +33,17 @@ internal static class RustFingerprintScanner
                 continue;
             }
 
-            if (TryParse(path, out var record))
+            if (!RustFileCacheKey.TryCreate(path, out var key))
+            {
+                continue;
+            }
+
+            var record = Cache.GetOrAdd(
+                key,
+                static (_, state) => ParseFingerprint(state),
+                path);
+
+            if (record is not null)
             {
                 results.Add(record);
             }
@@ -40,10 +52,8 @@ internal static class RustFingerprintScanner
         return results;
     }
 
-    private static bool TryParse(string path, out RustFingerprintRecord record)
+    private static RustFingerprintRecord? ParseFingerprint(string path)
     {
-        record = default!;
-
         try
         {
             using var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
@@ -57,33 +67,31 @@ internal static class RustFingerprintScanner
             var (name, version, source) = ParseIdentity(pkgId, path);
             if (string.IsNullOrWhiteSpace(name))
             {
-                return false;
+                return null;
             }
 
             var profile = TryGetString(root, "profile");
             var targetKind = TryGetKind(root);
 
-            record = new RustFingerprintRecord(
+            return new RustFingerprintRecord(
                 Name: name!,
                 Version: version,
                 Source: source,
                 TargetKind: targetKind,
                 Profile: profile,
                 AbsolutePath: path);
-
-            return true;
         }
         catch (JsonException)
         {
-            return false;
+            return null;
         }
         catch (IOException)
         {
-            return false;
+            return null;
         }
         catch (UnauthorizedAccessException)
         {
-            return false;
+            return null;
         }
     }