pyproject: add config file This will tell pip et al to call our setup.py for the majority of packaging concerns, but also gives us a place to put standard config stuff like black. This was previously D9833, but was rolled back due to test breakage. nbjoerg thinks that breakage is now resolved, so we're trying again. Differential Revision: https://phab.mercurial-scm.org/D10184

perf-util: add an helper revset to use the same spec as the case search script This make result of the searcher script easier to use. Differential Revision: https://phab.mercurial-scm.org/D10228