Standalone python script

[will-moore]

As part of the work to support figure usage and PDF/TIFF generation with OME-Zarr data (without using OMERO),
this PR focusses on the Figure_To_Pdf.py (see #619 for front-end changes).

We want to be able to use the same PDF/TIFF generation code both in OMERO and as a stand-alone script (in a python environment that doesn't have omero-py installed, but has zarr, dask etc instead).

Basic idea is that you go to a stand-alone OMERO.figure app (from #619) e.g. https://will-moore.github.io/omero-figure/?file=https://gist.githubusercontent.com/will-moore/fe0e260544b46af6e1e523b288fc85bc/raw/30547e61d4d8753ef0016f0a70435f1aafb43c2f/OMERO.figure_NGFF_demo.json and File > Save to download the figure.json file.
NB: LUTs not yet supported for Zarrs

Then, you run:

# doesn't need omero-py
# All images in figure are zarr images

$ python omero_figure/scripts/omero/figure_scripts/Figure_To_Pdf.py /Users/wmoore/Desktop/FIGURE/figure_json/OME-Zarr_demo.json

Another option supported by this PR is to download figure json from /figure app that is running from omero-web and contains OMERO images (use File > Export as JSON then save to a local file). Then, to generate the PDF, you can run the script with a connection to omero, with --omero option:

# needs omero-py - will use omero_cli to connect
# figure has images from OMERO

$ python omero_figure/scripts/omero/figure_scripts/Figure_To_Pdf.py /Users/wmoore/Desktop/FIGURE/figure_json/my_figure.json --omero

TODO:

• Support LUTs for zarrs (or ignore)?
• pip install omero-figure options for installing omero-web app (do we need to specify omero-web as dependency?) OR as a script (dependencies include reportlab, markdown, zarr, dask, requests, aiohttp, pillow`