#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/controller/web/DatabaseWebController.java

@@ -11,17 +11,17 @@ import org.springframework.web.bind.annotation.GetMapping;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
 import jakarta.servlet.http.HttpServletRequest;
-import stirling.software.SPDF.config.security.database.DatabaseBackupHelper;
+import stirling.software.SPDF.config.security.database.DatabaseService;
 import stirling.software.SPDF.utils.FileInfo;
 
 @Controller
 @Tag(name = "Database Management", description = "Database management and security APIs")
 public class DatabaseWebController {
 
-    private final DatabaseBackupHelper databaseBackupHelper;
+    private final DatabaseService databaseService;
 
-    public DatabaseWebController(DatabaseBackupHelper databaseBackupHelper) {
-        this.databaseBackupHelper = databaseBackupHelper;
+    public DatabaseWebController(DatabaseService databaseService) {
+        this.databaseService = databaseService;
     }
 
     @PreAuthorize("hasRole('ROLE_ADMIN')")
@@ -34,9 +34,9 @@ public class DatabaseWebController {
         } else if (confirmed != null) {
             model.addAttribute("infoMessage", confirmed);
         }
-        List<FileInfo> backupList = databaseBackupHelper.getBackupList();
+        List<FileInfo> backupList = databaseService.getBackupList();
         model.addAttribute("backupFiles", backupList);
-        model.addAttribute("databaseVersion", databaseBackupHelper.getH2Version());
+        model.addAttribute("databaseVersion", databaseService.getH2Version());
         return "database";
     }
 }