feat(firebaseAdmin): fix to pass user custom user claims to createCustomToken

[takashi]

As refer to the discussion https://github.com/gladly-team/next-firebase-auth/issues/317, currently we can not retrieve custom user claims that sets on firebase user from the custom token that created in server side.

So, I added the second argument for adding custom claims.

Please tell me if I send this PR by wrong manner for this repository 🙇

Thanks for great library!

[vercel[bot]]

@takashi is attempting to deploy a commit to the Gladly Team on Vercel.

A member of the Team first needs to authorize it.

[kamami]

Waiting for this :)

[tombouquet]

Any updates on this? Ran into this issue today.

[kmjennison]

Closed in favor of #654.