ResourceHandler.createResource methods should throw NPE

ResourceHandler.createResource methods should throw NPE.

Looking at the JavaDoc for the ResourceHandler we need to throw an NPE when the resourceName is null:

https://javaee.github.io/javaee-spec/javadocs/javax/faces/application/ResourceHandler.html#createResource-java.lang.String-

https://javaee.github.io/javaee-spec/javadocs/javax/faces/application/ResourceHandler.html#createResource-java.lang.String-java.lang.String-

https://javaee.github.io/javaee-spec/javadocs/javax/faces/application/ResourceHandler.html#createResource-java.lang.String-java.lang.String-java.lang.String-

Throws:
NullPointerException - if resourceName is null.

Currently our behavior looks to just return null which is incorrect according to the specification.