Export types via root export

[dnjstrom]

When using this package I quickly found myself wanting to use the ObjectToCamel type (and friends) to type my functions, and while they can be imported as

import type { ObjectToCamel } from 'ts-case-convert/lib/caseConvert'

I'd feel more secure relying on them if they were exported as part of the public api, i.e.

import type { ObjectToCamel } from 'ts-case-convert'

Are you open to making the types importable like that? If so, I can prepare a PR 👍

[real2two]

+1 I'd very much like this as well.