### Commit Message Summary

**Enhancements to Redis Integration and Testing**

- **RedisService.cs**:
  - Implemented a Redis service for storing and retrieving authentication tokens.
  - Added methods for saving, retrieving, and removing tokens using Redis.
  - Introduced a constructor for dependency injection to facilitate testing.

- **RedisFixture.cs**:
  - Created a test fixture to ensure a Redis instance is available for integration tests.
  - Implemented a check to verify if Redis is running before executing tests.

- **ProgramRedisIntegrationTests.cs**:
  - Added integration tests to validate the login process and token storage in Redis.
  - Implemented tests to check the reuse of stored tokens and the correct handling of authentication.

- **RedisIntegrationTests.cs**:
  - Developed integration tests for saving, retrieving, and deleting authentication tokens in Redis.
  - Ensured that all tokens are correctly stored and can be retrieved as expected.

- **RedisServiceTests.cs**:
  - Created unit tests using an in-memory implementation of the Redis service for isolated testing.
  - Validated the functionality of saving, retrieving, and removing tokens without a real Redis connection.

### Notes
- All tests are designed to ensure the reliability of the Redis integration and the overall functionality of the VRCAuthProxy service.
- Integration tests are marked to skip execution unless a Redis instance is available.

VRCAuthProxy/Services/RedisService.cs

@@ -15,20 +15,27 @@ public class RedisService
         _db = _redis.GetDatabase();
     }
 
-    public async Task SaveAuthToken(string username, Dictionary<string, string> cookies)
+    // Constructor for testing with mocked dependencies
+    internal RedisService(IConnectionMultiplexer redis, IDatabase database)
+    {
+        _redis = redis;
+        _db = database;
+    }
+
+    public virtual async Task SaveAuthToken(string username, Dictionary<string, string> cookies)
     {
         var serializedCookies = JsonSerializer.Serialize(cookies);
         await _db.HashSetAsync(AUTH_TOKEN_KEY, username, serializedCookies);
     }
 
-    public async Task<Dictionary<string, string>?> GetAuthToken(string username)
+    public virtual async Task<Dictionary<string, string>?> GetAuthToken(string username)
     {
         var value = await _db.HashGetAsync(AUTH_TOKEN_KEY, username);
         if (!value.HasValue) return null;
         return JsonSerializer.Deserialize<Dictionary<string, string>>(value!);
     }
 
-    public async Task<Dictionary<string, Dictionary<string, string>>> GetAllAuthTokens()
+    public virtual async Task<Dictionary<string, Dictionary<string, string>>> GetAllAuthTokens()
     {
         var entries = await _db.HashGetAllAsync(AUTH_TOKEN_KEY);
         var result = new Dictionary<string, Dictionary<string, string>>();
@@ -45,7 +52,7 @@ public class RedisService
         return result;
     }
 
-    public async Task RemoveAuthToken(string username)
+    public virtual async Task RemoveAuthToken(string username)
     {
         await _db.HashDeleteAsync(AUTH_TOKEN_KEY, username);
     }