feat: Refaktorierung von ClientEvents zur Verwendung eines Delegaten für öffentliche Schlüsselaktualisierungen

- Ersetzt `Action<string, string, string, ILogger?>` durch den `ClientEvent`-Delegaten für eine bessere Struktur.
- `ClientEvent`-Delegaten mit `AuthClient`-Referenz eingeführt, um öffentliche Schlüssel direkt zu aktualisieren.

DigitalData.Auth.Client/ClientEvents.cs

@@ -1,10 +1,18 @@
-using Microsoft.Extensions.Logging;
+using DigitalData.Core.Abstractions.Security;
+using Microsoft.Extensions.Logging;
 
-namespace DigitalData.Auth.Client
+namespace DigitalData.Auth.Client;
+
+public delegate void ClientEvent(AuthClient client, string issuer, string audience, string content, ILogger? logger = null);
+
+public static class ClientEvents
 {
-    public class ClientEvents
+    public static readonly ClientEvent UpdatePublicKeys = (client, issuer, audience, content, logger) =>
     {
-        public Action<string, string, string, ILogger?> OnMessageReceived { get; set; } = (issuer, audience, key, logger)
-            => logger?.LogInformation("Public key value has been updated. Issuer: {Issuer}, Audience: {Audience}, New Key: {Key}", issuer, audience, key);
-    }
+        if(client.PublicKeys.TryGet(issuer, audience, out var publicKey))
+            publicKey.Content = content;
+        else
+            logger?.LogWarning(
+                "Failed to update public key: No matching key found. Issuer: {Issuer}, Audience: {Audience}. Ensure the key exists before attempting an update.", issuer, audience);
+    };
 }