This change converts redundant attribute assignments of the form `a =
a;` or `a = someSet.a;` into cleaner `inherit` statements. This reduces
verbosity and follows common Nix style for bringing attributes into
scope.
Statix Codes: W03 (manual_inherit), W04 (manual_inherit_from)
Also include statix and the rule in our configuration.
Using ./. forces Nix to copy the flake to the store a second time.
Using bulitins.path like this, forcing the name to be "source", reduces the extraneous copy.
