Re-add legacy fib file support to reader
Use file extensions in the order they were added
Merge branch 'bug-18335-legacy-fib-files-no-longer-supported'
Merge branch 'bug-18353-port-diffusion-readers-writers'
Use IOUtil to write data

Define default extensions for diffusion file types
Merge branch 'bug-18352-diffusion-mini-apps-fail-to-write-outputdata'