Find a more elegant way to get the file path of results files and their expected counterparts during testing

[yezr]

More than one comment on #894 felt that the OutputFileIdentifiers class not having enough information at its instantiation to know the ultimate file path of the on disk files should be addressed. It seems like this is related to the expectation in the tests that the expected results to check against are located at the same path but with an "expected" modifier in the file name.

Can we think of an elegant way to address both of these?

[yezr]

Set to not in scope for 2.0