[Backend] New backend support of OMERO server

[Mr-Milk]

Allow the user to open an image from OMERO URL, try opening this URL in QuPath: https://idr.openmicroscopy.org/webclient/img_detail/9846423/?dataset=10801

The official IDR server is built upon Django with a Python API binding of the Omero client, https://github.com/ome/omero-py

For simple analysis, the user can try out data without downloading the whole image.