Improve "omero login" prompt

[pwalczysko]

omero login
Previously logged in to outreach.openmicroscopy.org:4064 as trainer-1
Server: [outreach.openmicroscopy.org:4064]

See https://forum.image.sc/t/download-full-projects-with-their-datasets/56434/9 and also some experience during outreach is suggesting that the prompt as above is not perceived by a naive user as one which they can overwrite.

Suggestion :

• Add a hinting message

omero login
Previously logged in to outreach.openmicroscopy.org:4064 as trainer-1
Hit Enter to accept value or type in your own:
Server: [outreach.openmicroscopy.org:4064]

cc @joshmoore

[joshmoore]

Transferred issue since the related change would need to be inserted at approximately https://github.com/ome/omero-py/blob/master/src/omero/plugins/sessions.py#L475, but likely conditionally since with all values were passed, nothing needs setting.

[joshmoore]

You can see https://github.com/willmcgugan/rich#readme for features that you can potentially request (see #217)

[dominikl]

Imo listing the default in [ ] and accepting it with a simple return or changing it by typing something else, is pretty standard CLI behaviour.