Hi ITN: Implement Roman class

[mayuris-00]

What does this PR do ?

Implement a Hindi inverse text normalization (ITN) Roman numeral class. It converts spoken numbers that follow a small, fixed set of context key words (chapter / section / class numbering) into Roman numerals.

The conversion is deliberately restricted to these predictable contexts; regnal, papal and product names (e.g. भास्कर-II) are a documented limitation because the same spoken number is ambiguous between Arabic and Roman form.

अध्याय तीन    -> अध्याय III
कक्षा बारह    -> कक्षा XII
खंड पाँच      -> खंड V
अध्याय निन्यानवे -> अध्याय XCIX

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• Do all unittests finish successfully before sending PR? (pytest --cpu tests/nemo_text_processing/hi/test_roman.py)
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PR Type:

• New Feature
• Bugfix
• Documentation
• Test