feat: add English ITN core rules (cardinal, ordinal, decimal)

[pengzhendong]

Summary

Add core English inverse text normalization rules:

• Cardinal: up to sextillion, eleven hundred pattern, minus/negative, and-deletion
• Ordinal: first→1st, second→2nd, thirteenth→13th, twenty first→21st
• Decimal: twelve point five→12.5, point o five→.05, minus three point one four→-3.14
• Char: fallback for unmatched characters

Examples

from itn.english.rules.inverse_normalizer import InverseNormalizer
n = InverseNormalizer()
n.normalize("twenty three")                    # 23
n.normalize("one hundred and one")             # 101
n.normalize("eleven hundred")                  # 1100
n.normalize("minus forty two")                 # -42
n.normalize("first")                           # 1st
n.normalize("twelve point five")               # 12.5
n.normalize("hello world twenty three")        # hello world 23

NeMo cardinal test: 27/29 passed.

Test plan

• All 1400 unit tests pass
• CI passes