Generate pyproject dependencies with dfg

[vyasr]

This PR uses dependencies.yaml to generate the dependency lists in pyproject.toml

[vyasr]

I left a few questions as inline comments but will replicate them here for convenience:

• Some of the runtime requirements like seaborn and scipy seem like they could be optional, but I don't know if that's of interest to the cuml devs right now. There are enough conditional imports happening in the package that I couldn't sort through all of them. seaborn and scipy were particular examples that seemed like they could plausibly be optional.
• The hdbscan packages on conda-forge and pypi are getting out of sync. The pypi package is no longer that out of date (there was a release in October) but the conda-forge package is now quite old due to pulling from a fork instead of the main repo. Do we need to take any action here? Does dependencies.yaml need to stay bifurcated, or can we simply pull the package using the name in both cases and move on now?
• Is there a plan for dask-glm since the repo is archived now?

[vyasr]

/merge