Make Picture Entity Card templatable

[manutenfruits]

I want to use the URL of a sensor attribute as the state_image in the Picture Entity Card, if it supported templates this would be great.

Sample use cases:

• Scraper custom sensors that retrieve the URL of an image that changes over time.

[djbx83]

This would be very useful, especially when you have an image URL inside an attribute.
For example, I have a http-rest sensor that exposes an image inside a json and I'm going crazy to display this image in a dashboard.
If picture-entity was templetable, it would solve a lot of headaches...