Partial rebase of 4744 Use client-side protocol/host in URL

[manics]

Partial rebase of #4744

What this PR does

The web metadata panel Link to this <object> contains a server side URL created from the HTTP Host header. This causes problems with server-side caching.

• Wherever possible client-side URLs should be constructed in javascript using the location object, so that the /path will be cached but the protocol://host will be handled by the client browser

Testing this PR

1. Setup OMERO.web, optionally with a public user (makes testing easier)
2. Check Link to this <object> in the web RH metadata panel. The URL should use whatever the browser has in the location bar, and in additional examination of the returned html such as http://host/webclient/metadata_details/image/ID/ should show var lnk = location.protocol + "//" + location.host + "/webclient/"; instead of a URL.

The following additions from #4744 related to twitter/opengraph support (#4613) have not been rebased:

• URLs in embedded non-javascript metadata such as URLs parsed by social media can be overridden using omero.web.ui.omero.web.ui.external_link_baseurl (this must include the protocol).

Related reading

Link to cards, tickets, other PRs:

• See https://trello.com/c/KETiUCeR/373-metadata-cache-refresh-incorrect-link-to for a particular use-case

Note

The only other place I'm aware of that let's you copy a link is in the full image viewer where it is already generated by client-side javascript: https://github.com/manics/openmicroscopy/blob/metadata52-linkto/components/tools/OmeroWeb/omeroweb/webgateway/templates/webgateway/viewport/omero_image.html#L665

This is unchanged, but maybe it should be unified?

[manics]

Partially
--rebased-from #4744

[will-moore]

Sorry - missed this yesterday. Looking now...

[will-moore]

Not sure that I understand the "problems with server-side caching" but this certainly seems to be working fine.
On cowfish I see

var lnk = location.protocol + "//" + location.host + "/webmerge/webclient/";

and all the link functionality works fine as described.

Good to merge.

[joshmoore]

Not sure that I understand the "problems with server-side caching" but this certainly seems to be working fine.

@will-moore, the problem we were seeing is that the URL that someone used to access a resource (http://idr-demo.openmicroscopy.org/webclient/?show=plate-2551 vs http://idr-demo2.openmicroscopy.org/webclient/?show=plate-2551, aliases for each other) was being stored in the metadata cache for the right-hand panel.