Add generation of JSON for AlphaFold server

[jkosinski]

We could have a mode in which, instead of submitting AF2 jobs, we save a JSON for batch mode on the AlphaFold server.

Here is more information:
https://golgi.sandbox.google.com/faq says that:
Can I import job files into AlphaFold Server?
Yes, we support efficiently importing multiple draft jobs by uploading JSON files with up to 100 jobs per file. Please note that you have a storage capacity of up to 500 saved drafts in your history, so be mindful to manage your uploads to stay within the limit.

To create a JSON file: please refer to this example for the JSON file syntax. Inside each .zip file with modeling results, you'll find a JSON file named ’job_name_job_request.json’ containing the job inputs. These files offer a convenient starting point for generating new jobs as they are easily editable in standard text editors or in a programming system like Google Colab notebooks.

Once your file is prepared click the 'Upload JSON’ button to upload your JSON files. Imported jobs will appear as saved drafts in your job history and you can click on (three dots) of your job to edit or run them.

Here are instructions:
https://github.com/google-deepmind/alphafold/blob/main/server/README.md