Web fs image links

This is a clean-up of the previous port of Fileset functionality from FS to dev_4_4 https://github.com/openmicroscopy/openmicroscopy/pull/759

Now, we don't carry over any of the changes to the Blitz Gateway. Also remove references to 'FS' in the web templates (although we keep options for showing original File Paths, even though this isn't used).

This PR on dev_4_4 corresponds to 2 PRs in develop:

Originally https://github.com/openmicroscopy/openmicroscopy/pull/672 and then clean-up
https://github.com/openmicroscopy/openmicroscopy/pull/778