feat(get-info-on-pdf): use PDFBox preflight to validate PDF compliancy level, and parse in compliancy type (#4595)

# Description of Changes

- Refactored methods for parsing and extracting PDF/A conformance levels
from XMP metadata.
- Implemented PDF/A validation using Preflight from Apache PDFBox.
- Enhanced PDF information generation to include PDF/A conformance level
and validation results.
- Updated compliance checks and JSON output to reflect new PDF/A
capabilities.

### Test files:

[lorem-ipsum_PDFA1b.pdf](https://github.com/user-attachments/files/22687689/lorem-ipsum_PDFA1b.pdf)

[lorem-ipsum_PDFA_2b.pdf](https://github.com/user-attachments/files/22687692/lorem-ipsum_PDFA_2b.pdf)

[lorem-ipsum_PD⁄A3a.pdf](https://github.com/user-attachments/files/22687693/lorem-ipsum_PD.A3a.pdf)

### New results:
<img width="699" height="257" alt="image"
src="https://github.com/user-attachments/assets/b8cb5510-2908-4e08-97f6-d5799e0e1be7"
/>
<img width="699" height="257" alt="image"
src="https://github.com/user-attachments/assets/d7af3731-ad19-4524-b1c1-32f47776e6af"
/>
<img width="699" height="257" alt="image"
src="https://github.com/user-attachments/assets/6e48e65b-2ebc-402a-a222-bfdbf783e45d"
/>

I also validated with online tools. Should be good now!

I was also thinking moving this to GeneralUtils; it may be useful for
PDF/A converter in the future, or for other features. Not sure yet, for
now I think this is good for now.

Closes #4568

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- Why the change was made
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---

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

### Documentation

- [ ] 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)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [x] 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/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Signed-off-by: Balázs Szücs <bszucs1209@gmail.com>

app/common/src/main/java/stirling/software/common/util/RegexPatternUtils.java

@@ -447,7 +447,20 @@ public final class RegexPatternUtils {
         return getPattern("@\\s*([^\\s\\(]+(?:\\.[a-zA-Z0-9]+)?)");
     }
 
-    // API doc parsing patterns
+    /** Pattern for matching pdfaid:part attribute in XMP metadata */
+    public Pattern getPdfAidPartPattern() {
+        return getPattern("pdfaid:part[\"\\s]*=[\"\\s]*([0-9]+)");
+    }
+
+    /** Pattern for matching pdfaid:conformance attribute in XMP metadata */
+    public Pattern getPdfAidConformancePattern() {
+        return getPattern("pdfaid:conformance[\"\\s]*=[\"\\s]*([A-Za-z]+)");
+    }
+
+    /** Pattern for matching slash in page mode description */
+    public Pattern getPageModePattern() {
+        return getPattern("/");
+    }
 
     /**
      * Pre-compile commonly used patterns for immediate availability. This eliminates first-call