SSO Refactoring (#2818)

# Description of Changes

* Refactoring of SSO code around OAuth & SAML 2
* Enabling auto-login with SAML 2 via the new `SSOAutoLogin` property
* Correcting typos & general cleanup

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [x] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [x] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [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)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

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

src/main/java/stirling/software/SPDF/config/AppConfig.java

@@ -35,10 +35,7 @@ public class AppConfig {
     }
 
     @Bean
-    @ConditionalOnProperty(
-            name = "system.customHTMLFiles",
-            havingValue = "true",
-            matchIfMissing = false)
+    @ConditionalOnProperty(name = "system.customHTMLFiles", havingValue = "true")
     public SpringTemplateEngine templateEngine(ResourceLoader resourceLoader) {
         SpringTemplateEngine templateEngine = new SpringTemplateEngine();
         templateEngine.addTemplateResolver(new FileFallbackTemplateResolver(resourceLoader));
@@ -129,8 +126,8 @@ public class AppConfig {
     }
 
     @ConditionalOnMissingClass("stirling.software.SPDF.config.security.SecurityConfiguration")
-    @Bean(name = "activSecurity")
-    public boolean missingActivSecurity() {
+    @Bean(name = "activeSecurity")
+    public boolean missingActiveSecurity() {
         return false;
     }