* If token and attributes are the same, return endpoint
* fix black
* moto sns platform_endpoint.attributes includes only token,enabled
* add tests when calling sns#create_platform_endpoint with same attrs for #4056
The response returned for sns.get_endpoint_attributes was not in
sync with the actual response from boto.
Co-authored-by: Antillon, Alejandro <alejandro.antillon@f-secure.com>