feat: Added edge case tests for international phone number formats

[thisusedtobekshitijshresth]

• Tests handle real-world edge cases like special characters, multiple spaces, and format variations.
• Added parsing tests with various separators, extensions and malformed inputs.
• Added formatting tests across national, international, E164, and RFC3966 styles.
• Added validation tests with length validation and cross-region scenarios.
• Covers major international regions of US, UK, Germany, India, Brazil, Japan.

[dwbruhn]

@khresth thank you for the tests, but they're incorrect (see the CI output).