Function normalizeGender

normalizeGender(input: unknown): Gender | null
Normalizes any English, Sinhala, or Tamil representation of gender into 'male' | 'female'. Returns null if unrecognized.
Parameters
- input: unknown
  Gender in English, Sinhala, or Tamil, including common abbreviations such as 'M' or 'F'.
Returns Gender | null
'male', 'female', or null if not recognised.
Example
```
normalizeGender('F'); // 'female'
normalizeGender('Male'); // 'male'
normalizeGender('ගැහැණු'); // 'female'
normalizeGender('other'); // null
```
- Defined in gender/validator.ts:38