Add the ability to use existing icons for object types using External Import

Problem

At the moment, we cannot refer to existing icons present in JSM Assets to map them to an object type when defining the mapping in External Import as mentioned in the documentation.

The only way to do this is to download the icon from the Assets UI, get its base64 encoded value and then provide that when defining the mapping.

Suggested Solution

Provide a way to refer the existing icons present in JSM Assets

Why This Is Important

This will save the effort of downloading the icons, encoding them and then providing the value in schema mapping.

Workaround

1. Download the 48x48 icon from UI by going to Assets > Configuration > Global icons tab.
2. Convert the png image to base64 encoded value. The value obtained will be used in defining the icon as mentioned in the documentation.