[SDK-1924] client methods should handle partially filled arguments

[adamjmcgrath]

Description

getUser, getIdTokenClaims and getTokenWithPopup relies on a default object argument for it's defaults, this can be an issue when passing a partially filled or empty object argument eg getUser({}). This will not use the default object so not apply the default arguments.

References

See #554

Testing

Login to the SPA JS playground
call await auth0.getUser({})

Expected: an object containing your user data
Actual: undefined

• This change adds test coverage for new/changed/fixed functionality

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not master