Implement CamelCase<T> which converts snake_case string to camelCase.

For example

type camelCase1 = CamelCase<'hello_world_with_types'> // expected to be 'helloWorldWithTypes'
type camelCase2 = CamelCase<'HELLO_WORLD_WITH_TYPES'> // expected to be same as previous one

This challenge was ported from Type Challenges and was authored by antfu