Don't disable the histogram for big images

[will-moore]

See #641 and request at https://forum.image.sc/t/olympus-whole-slide-scanner-histogram-feature-not-available-in-omero-iviewer/56308/7

TODO: do the same for iviewer!

As @sbesson mentioned on that issue, the server does indeed support histograms on Big images!

To test:

• Show histogram on a big image

[imagesc-bot]

This pull request has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/olympus-whole-slide-scanner-histogram-feature-not-available-in-omero-iviewer/56308/10

[sbesson]

A few thoughts regarding scenarios that might be considered as part of the functional testing:

• the backend support was introduced in version 5.6.8 of OMERO.server - see https://www.openmicroscopy.org/2023/07/25/omero-5-6-8.html. Should OMERO.web perform checks to ensure the server has the necessary functionality for large tiles images? Or how would an exception thrown server-side be communicating to the end-user?
• there are some conditions under which the histogram will still return an exception, notably if the smallest resolution of the pyramid still exceeds the max plane requirements of the server. It should be fairly simple to emulate such a test case by using fake images with large sizeX/sizeY values and a low (but not 1) number of resolutions. As above, what would be the response of the UI to the ApiUsageException that should be returned by the server?

[will-moore]

To illustrate the 2nd point from @sbesson above: just reported at #663.
Need to handle that exception as well as exception from pre 5.6.8 servers (July 2023 release, bit hard to test with older server).

[will-moore]

We already handled the omero.ApiUsageException in the JSON loading.
With the exception message displayed in an alert() as added in this PR, it looks like this:

I expect we'd see the same thing with older servers that don't support big image pyramids too