update_interval for binary_sensor

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

Use the update_interval setting to cause a binary_sensor to send the state on the specified interval

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

When coding my motion sensors using C++, I included the function to send a state every 60 seconds. Then, in Home Assistant, I would expire the state after a few minutes. This would show if the sensor was no longer communicating with the host, and help show if wires had been cut or disconnected. Using an ESPHome based sensor, I have to remove the expire_after setting in Hass or the sensor will show as unavailable when there is no movement over a time longer that the expire interval.

An update_interval would serve as a heartbeat for the sensor hardware.

**Additional context**