Add data attributes for test support

[causztic]

• What does this PR do? Fixes https://github.com/devfolioco/react-otp-input/issues/96 Continues https://github.com/devfolioco/react-otp-input/pull/206

This PR aims to add data-cy support for cypress E2E tests, and data-testid for react-testing-library tests.

• Any background context you want to provide?

Am using this library right now, but with my E2E tests I had to target aria-label which is not very resilient to changes.

• Screenshots and/or Live Demo With data attributes set in the demo:

Without data attributes set in the demo:

[apollonian]

Thank you, @causztic!

[apollonian]

@all-contributors please add @causztic for code

[allcontributors[bot]]

@apollonian

I've put up a pull request to add @causztic! :tada: