Refs #5012 Add support for range searching in FileFinder.

This includes a new public method called getFullPaths that takes a comma
separated string for potential file paths attempts to find a match. If the
file path contains something that looks like a range it will expand the range
and look for each file in the range individually.
Refs #5012 Move file finding logic to be contained in FindFiles.

This includes modifying the widget to use the getFullPaths function to find
multiple file paths.
Refs #5012 Correct a seg fault with single file searching.
Refs #5012 Swap IDA interface to run LoadNexus C++ side.

This algorithm was being executed on a separate thread which was causing
the automatic file searching to play up in certain cases where it would
still be searching for files while the user had clicked the run button.

This change stops that from happening, but this should really be changed
to use AlgorithmRunner. But that's outside the scope of this ticket.
Refs #5012 Export method to python api.
Refs #5012 Throw NotFoundError instead of invalid argument.
Refs #5012 Add unit tests for new method.
Merge branch 'feature/5012_elwin_multiple_runs' into develop