Remove deprecated Authentication methods and add types

[joshcanhelp]

Changes

Breaking Changes

• Authentication class instantiation requires a client_id argument
• Removed deprecated Authentication::setApiClient() method
• Removed deprecated Authentication::authorize_with_ro() method
• Removed deprecated Authentication::authorize_with_accesstoken() method
• Removed deprecated Authentication::impersonate() method
• Removed deprecated Authentication::email_code_passwordless_verify() method
• Removed deprecated Authentication::sms_code_passwordless_verify() method
• Authentication::code_exchange() method now throws an ApiException if class-level client_secret is empty (would be throwing an error from the HTTP request failure before)
• Authentication::client_credentials() method now throws an ApiException if audience is empty

Other changes

• Authentication::get_authorize_link() now adds class-level scopes and audience if none are passed in
• Authentication::get_logout_link() will now accept true as the client_id parameter to use class-level value
• Parameter and return types
• Strict typing for Authentication class

Testing

• This change modifies test coverage
• This change has been tested on PHP 7.1

Checklist

• All existing and new tests complete without errors.
• The correct base branch is being used.

[github-actions]

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