We'll create local resources by application relative names. This routine gets passed a full virtual path to the page or template control and we'll strip off the virtual and use only the virtual relative path.
So: /myapp/test.aspx becomes test.aspx and /myapp/subdir/test.aspx becomes subdir/test.aspx
for our ResourceSet naming of local resources. The provider is created with this ResourceSet name.
public virtual IResourceProvider CreateLocalResourceProvider( string virtualPath );