add :resource multimethod for ring.util.response/resource-data

[yogthos]

When loading resources with GraalVM the protocol returned by the java.net.URL is "resource" instead of "jar". Mirroring the :jar resource-data multimethod would allow apps compiled with GraalVM to use wrap-resource to load resources from the image. Here's an example in a minimal project.

[cap10morgan]

Adding the suggested method worked for me. Time for a PR?

[agorgl]

Bumped into this too when trying to build native image of pedestal app that used resources