feat: add a client for Purdue Analysis Facility

[kondratyevd]

@oshadura @alexander-held following up on our chat last month:

This PR adds an option to run CMS OpenData workflow at Purdue Analysis Facility via Dask Gateway cluster.
The setup is similar to the cmsaf-dev option, the only differences are:

• The address of the Dask Gateway API server;
• The default number of workers is 10 to avoid using too much resources when running AGC as a "smoke test".

Additional info about the Dask Gateway setup at Purdue AF can be found here. At Purdue AF, we have two Dask Gateway instances - with SLURM and Kubernetes backends. The purdue-af AGC client will use the Kubernetes backend.

[oshadura]

LGTM!

[alexander-held]

Thanks for adding this!