Jupyter notebook preview export embed images

[ricklamers]

Description

Images referred to in markdown need to be rendered in the HTML preview. This enables the embed config option of nbconvert to resolve the path loading issues if images are not embedded.

Checklist

• I have manually tested my changes and I am happy with the result.
• The PR branch is set up to merge into dev instead of master.
• I haven't introduced breaking changes that would disrupt existing jobs, i.e. backwards compatibility is maintained.
• In case I changed the dependencies in any requirements.in I have run pip-compile to update the corresponding requirements.txt.

[ricklamers]

@fruttasecca we need to go to Flask>=2 to meet the Jinja>=3 requirement for the nbconvert version we need to support embedding images.

We depend on some Flask 1.X only features for flask_script which causes issues when upgrading to Flask>=2.

Traceback (most recent call last):                                                                                                     
  File "/orchest/services/orchest-webserver/app/migration_manager.py", line 2, in <module>                                             
    from flask_script import Manager                                                                                                   
  File "/usr/local/lib/python3.9/site-packages/flask_script/__init__.py", line 15, in <module>                                         
    from flask._compat import text_type                                                                                                
ModuleNotFoundError: No module named 'flask._compat'

Can we refactor flask_script / migration invocation to be able to use Flask>=2?

I'm OK with only doing this for orchest-webserver for the time being. If you'd prefer to also upgrade orchest-api and auth-server to Flask>=2 that would also work for me.

[mausworks]

LGTM! :)