#2270: External DB Support (#2457)

# Description

External DB support for Stirling PDF. You can now choose between the
default H2 or PostgreSQL by setting the new `enableCustomDatabase`
property to `true` or `false`.

To enable your own custom (PostgreSQL) database:
- Set `enableCustomDatabase` to `true`
- Add your database url to `customDatabaseUrl`
- Set your `username` and `password`

Closes #2270 

## Checklist

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have performed a self-review of my own code
- [x] I have attached images of the change if it is UI based
- [x] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [x] My changes generate no new warnings
- [x] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

src/main/java/stirling/software/SPDF/config/security/CustomLogoutSuccessHandler.java

@@ -20,7 +20,7 @@ import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
-import stirling.software.SPDF.SPdfApplication;
+import stirling.software.SPDF.SPDFApplication;
 import stirling.software.SPDF.config.security.saml2.CertificateUtils;
 import stirling.software.SPDF.config.security.saml2.CustomSaml2AuthenticatedPrincipal;
 import stirling.software.SPDF.model.ApplicationProperties;
@@ -110,7 +110,7 @@ public class CustomLogoutSuccessHandler extends SimpleUrlLogoutSuccessHandler {
 
             // Construct URLs required for SAML configuration
             String serverUrl =
-                    SPdfApplication.getStaticBaseUrl() + ":" + SPdfApplication.getStaticPort();
+                    SPDFApplication.getStaticBaseUrl() + ":" + SPDFApplication.getStaticPort();
 
             String relyingPartyIdentifier =
                     serverUrl + "/saml2/service-provider-metadata/" + registrationId;