Gets an image renderer for the specified data.
The data passed here will be part of the image URL following the prefix
that the provider was registered with. So for example, if the provider
was registered for the prefix
custom, and the image to be
rendered in the Markdown document was
[blah](custom:the data],
then the string passed where would be
the data.
If there is no appropriate image renderer (for example, for the built-in
item stack renderers: if the item definition is invalid), this should
return
null, it should
never throw an exception.