Enable OpenSSF Scorecard Action and badge

[joycebrum]

I'd like to suggest the tensorflow I/O to enable the Scorecard Action and add its badge to the README file.

The Scorecard Action runs some checks that verifies ways the project can improve its supply chain security posture, such as looking for dangerous paterns on workflows, vulnerabilities on dependencies or for a security policy. Besides, the action allows to add the badge to readme page (such as the one on tensorflow/tensorflow) that shows the project's score for users.

I'll be opening a PR with the config file, let me know if you have any questions or concerns.

Thanks!