Rather than writing output to stdout, allow specifying an output file

This is a prereq for generating intermediate results when processing a large or continuous audit stream

Could either generate everything into a single file, or generate a file per type (clusterroles, roles, clusterrolebindings, rolebindings)... not sure which is better.

When generating, would generate to a tmp file, then do an atomic move into place, so an apply loop operating on the file would never get a partially written file.