This issue tracks porting the UnitarySynthesis pass to rust as part of the #12208 epic. This pass in particular will still always require a fairly large python component, as the unitary synthesis plugin interface necessitates a Python execution mode. But when the a plugin is not specified we shouldn't need to use python at all. The other option is we can call Python from rust to pass a unitary array to the plugins and then operate exclusively from rust otherwise as well.