Add tests and implement StubBearer authentication for Signer endpoints

- Created SignerEndpointsTests to validate the SignDsse and VerifyReferrers endpoints.
- Implemented StubBearerAuthenticationDefaults and StubBearerAuthenticationHandler for token-based authentication.
- Developed ConcelierExporterClient for managing Trivy DB settings and export operations.
- Added TrivyDbSettingsPageComponent for UI interactions with Trivy DB settings, including form handling and export triggering.
- Implemented styles and HTML structure for Trivy DB settings page.
- Created NotifySmokeCheck tool for validating Redis event streams and Notify deliveries.

NuGet.config

@@ -2,16 +2,16 @@
 <configuration>
   <packageSources>
     <clear />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
     <add key="local" value="local-nuget" />
-    <add key="mirror" value="https://mirrors.ablera.dev/nuget/nuget-mirror/v3/index.json" />
   </packageSources>
   <packageSourceMapping>
+    <packageSource key="nuget.org">
+      <package pattern="*" />
+    </packageSource>
     <packageSource key="local">
       <package pattern="Mongo2Go" />
       <package pattern="Microsoft.Extensions.Http.Polly" />
     </packageSource>
-    <packageSource key="mirror">
-      <package pattern="*" />
-    </packageSource>
   </packageSourceMapping>
 </configuration>