Grow Fingerprint Sensor - Sensing Pin as Binary Sensor

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

Last year it was possible to have a gpio binary sensor watching the sensing pin and having it configured in the fingerprint component at the same time.
This has been "fixed" in a update (I think at the beginning of this year) and now is there no way to get the pin state elsewhere.

It would be awesome if I could configure a binary sensor in the fingerprint component and have this available for the rest of the esphome code (like lambda).

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

I have programmed "advanced" animations for my fingerprint sensors, some of them rely on the status of the sensing pin.
I tried getting the state using lambda (id(fingerpint_sensor)->sensing_pin_->digital_read()) but the sensing_pin_ is protected.
Now I created a custom component and made it public to get around.

**Additional context**

Grow Fingerprint Sensor Component

Start with the Grow Fingerprint Sensor Component and inspect how its sensing pin is configured alongside the GPIO binary sensor. Review the existing lambda and custom-component workarounds described in the issue, then determine how the sensing-pin state could be made available to the rest of the ESPHome configuration. Done means the sensing state can be configured in the fingerprint component and consumed elsewhere.

Written by the indexing model from the issue text.