refactor: AsymmetricPublicKey durch ClientPublicKey ersetzt und RSA-Schlüsselverwaltung verbessert

- `AsymmetricPublicKey` in `ClientPublicKey` umbenannt
- `ClientPublicKey` von `RSAKeyBase` abgeleitet für RSA-Funktionalität
- Dynamischen PEM-Import in `UpdateContent` hinzugefügt

DigitalData.Auth.Client/ClientPublicKey.cs

@@ -0,0 +1,34 @@
+using DigitalData.Core.Abstractions.Security;
+using DigitalData.Core.Security.RSAKey;
+
+namespace DigitalData.Auth.Client;
+
+/// <summary>
+/// Represents a public RSA key, allowing dynamic updates and PEM import functionality.
+/// </summary>
+public class ClientPublicKey : RSAKeyBase, IAsymmetricPublicKey, IAsymmetricKey, IUniqueSecurityContext
+{
+    public required string Issuer { get; init; }
+
+    public required string Audience { get; init; }
+
+    private string _content = string.Empty;
+
+    public override string Content
+    {
+        get
+        {
+            return _content;
+        }
+        init
+        {
+            UpdateContent(value);
+        }
+    }
+
+    public void UpdateContent(string content)
+    {
+        _content = content;
+        RSA.ImportFromPem(content);
+    }
+}