Binary sensor for light state

**Describe the problem you have/What new integration you would like**

Allow light as a source for copy binary sensor

**Please describe your use case for this integration and alternatives you've tried:**

**Additional context**

There is a similar binary sensor for switch - https://github.com/esphome/feature-requests/issues/2957

Start by reviewing the linked switch binary-sensor request at feature-requests/issues/2957 and compare its proposed behavior with this request. Identify the existing light and copy binary sensor entry points in the implementation; done means a light can reliably serve as a copy binary sensor source with documented behavior and coverage for the relevant states.

Written by the indexing model from the issue text.