Fix: Access to Swagger UI when login enabled (#5194)

Fixes for /swagger-ui/index.html & /v1/api-docs endpoints not being
accessible when login was enabled.

- `UserAuthenticationFilter.isPublicAuthEndpoint()` had gaps in its
check, missing `/v1/api-docs`
- Refactored `UserAuthenticationFilter` to use
`RequestUriUtils.isPublicAuthEndpoint()` instead of its own incorrect
method

Closes #5125 & #5028

---

### Testing (if applicable)

- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

app/core/src/main/java/stirling/software/SPDF/config/OpenApiConfig.java

@@ -62,10 +62,14 @@ public class OpenApiConfig {
 
         // Add server configuration from environment variable
         String swaggerServerUrl = System.getenv("SWAGGER_SERVER_URL");
+        Server server;
         if (swaggerServerUrl != null && !swaggerServerUrl.trim().isEmpty()) {
-            Server server = new Server().url(swaggerServerUrl).description("API Server");
-            openAPI.addServersItem(server);
+            server = new Server().url(swaggerServerUrl).description("API Server");
+        } else {
+            // Use relative path so Swagger uses the current browser origin to avoid CORS issues when accessing via different ports
+            server = new Server().url("/").description("Current Server");
         }
+        openAPI.addServersItem(server);
 
         // Add ErrorResponse schema to components
         Schema<?> errorResponseSchema =