Xopt Importer; Problem Wrapper

[electronsandstuff]

This PR adds in a problem wrapper for Xopt as well as tools to load data from its output.

• New wrapper class XoptProblemWrapper
• New importer import_cnsga_history for CNSGA generator
• New importer import_nsga2_history for NSGA2 generator and convenience function import_nsga2_history_dir which accepts output_dir
• Unit tests for wrappers and importers
• Modernize test dependencies, python tests Github workflow.

TODO

• Add unit test for import_cnsga_history
• Check VOCs names are carried over
• Check VOCs directions/ constraints are set correctly
• Add unit test for XoptProblemWrapper
• Add function to load from NSGA2Generator output directory