Enhance Adaptive Image Servlet to support Synthetic Image resources

## Feature Request

**Is your feature request related to a problem? Please describe.**
The imageDelegation used by Teaser component is a good feature which can be used by custom AEM components. But, to use it today, the component needs to extend Image WCM core component.
This becomes a problem, when you component already extends an another component. Say I want to extend content fragment component to display Adaptive Image. Since, I need to extend CF component, I can't extend the Image component.

**Describe the solution you'd like**
After using imageDelegation the srcset is created, but the Image rendering fails (404).
It would be good if Adaptive Image Servlet could also deal with Synthetic Image Resource. That is we could avoid extending Image component.

**Are there alternatives?**
Extending Adaptive Image component. But, its a challenge when your custom component needs to extend something else.

**Documentation**
The user would be able to render Adaptive images by Syncthetic Image resources.

Start by locating the Adaptive Image Servlet and the imageDelegation handling described in the issue, then inspect any related tests for resource rendering. Determine how Synthetic Image resources are represented and verify the result by rendering an adaptive image without a 404, including coverage for the new resource type.

Written by the indexing model from the issue text.