feat: Add XML to JSON converter

[HamdiSaidaniX]

Added new XML to JSON converter utility with full SEO content and related tool links.

[peckz]

@HamdiSaidaniX Thank you!
I suggest extracting those functions into a helper file and adding a couple of tests to make sure everything is running smoothly!

You can find an example in json-to-csv.utils.ts and json-to-csv.test.ts

[HamdiSaidaniX]

@peckz Thank you for the feedback! I've made the following updates:

✅ Extracted xmlToJson function into a separate helper file (lib/xmlToJson.ts)
✅ Added comprehensive unit tests covering basic conversion, attributes, arrays, text content, and error handling

Let me know if there's anything else you'd like me to adjust!