Add note about zarr etc requirement for export script with zarr images

[will-moore]

Document need for export script to install zarr if figure has zarr images.

Currently script fails to import zarr, so will error if it contains zarr images (see below).

I guess we could have it silently skip OME-zarr images if zarr import fails?

Traceback (most recent call last):
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 3562, in <module>
    handle_main()
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 3506, in handle_main
    run_script()
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 3485, in run_script
    file_annotation = export_figure(conn, script_params)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 3437, in export_figure
    return fig_export.build_figure()
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 1257, in build_figure
    self.add_panels_to_page(panels_json, page)
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 2761, in add_panels_to_page
    pil_img = self.draw_panel(panel, page, i)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 2580, in draw_panel
    pil_img = self.get_panel_image(panel, orig_name)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 2492, in get_panel_image
    scale, pil_img = self.render_zarr_to_pil(panel)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/omero-x/omero/tmp/omero_omero-x/50918/processufqayf2_.dir/./script", line 2328, in render_zarr_to_pil
    import zarr
ModuleNotFoundError: No module named 'zarr'

cc @pwalczysko

[pwalczysko]

I guess we could have it silently skip OME-zarr images if zarr import fails?

That strongly resembles the discussion we had on the reportlab case, cc @Rdornier . I think it is better to have it properly failed rather than silently dropping data.

[pwalczysko]

like that, optional, indeed

[pwalczysko]

Tested the recommended workflow and indeed the pip install zarr dask fsspec[http] into the server venv solves the export of figures which contain zarr.
It also reads well.

Thank you

[will-moore]

@pwalczysko Sorry to add more to this PR, but since we're editing script install instructions.... I realised that the current workflow "upload script then dependencies" won't work on a fresh install since the upload will fail if you don't already have dependencies installed. So I've switched the order.

Also made it clearer that OME-Zarr support (for script export) is still in rc status. Don't want people getting confused before it's released proper.

[pwalczysko]

@pwalczysko Sorry to add more to this PR, but since we're editing script install instructions.... I realised that the current workflow "upload script then dependencies" won't work on a fresh install since the upload will fail if you don't already have dependencies installed. So I've switched the order.

Also made it clearer that OME-Zarr support (for script export) is still in rc status. Don't want people getting confused before it's released proper.

Yes, thanks, this is a clear logical swap and the highlight to RC is also helpful imho.