Add passwordless endpoints

[lbalmaceda]

Changes

This PR adds support for invoking the new passwordless endpoints. It also adds a small note on the readme about them and the grant type that must be enabled first.

There are some UX changes on the second request (the one that performs the authentication). The endpoint expects a username parameter, but I'm mapping it from either email or phoneNumber. The same happens with otp, which is getting mapped from code. Please, evaluate if this is desired or if it's only adding noise.

Any formatting change included on the diff is due to the pre-commit hook.

References

SDK-1281

Testing

I've tested the email passwordless manually on a sample app. Unit tests are included as well.

• This change adds unit test coverage
• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 general contribution guidelines
• All existing and new tests complete without errors
• All active GitHub checks have passed

[Widcket]

Most are non-blocking, except the doc comments regarding the usage of links in sms.

[Widcket]

There are some UX changes on the second request (the one that performs the authentication). The endpoint expects a username parameter, but I'm mapping it from either email or phoneNumber. The same happens with otp, which is getting mapped from code. Please, evaluate if this is desired or if it's only adding noise.

I think this is good from a UX perspective.

[Widcket]

There are a couple of leftover references that should be addressed.

[Widcket]

LGTM