feat(tactic/linter): add decidable_classical linter (#2352)
* feat(tactic/linter): add decidable_classical linter
* docstring
* cleanup
* fix build, cleanup
* fix test
* Update src/tactic/lint/type_classes.lean
Co-Authored-By: Scott Morrison <scott@tqft.net>
* Update src/tactic/lint/type_classes.lean
Co-Authored-By: Scott Morrison <scott@tqft.net>
* Update src/tactic/lint/default.lean
Co-Authored-By: Scott Morrison <scott@tqft.net>
* Update src/tactic/lint/type_classes.lean
Co-Authored-By: Scott Morrison <scott@tqft.net>
* Update src/data/dfinsupp.lean
Co-Authored-By: Yury G. Kudryashov <urkud@urkud.name>
Co-authored-by: Scott Morrison <scott.morrison@anu.edu.au>
Co-authored-by: Scott Morrison <scott@tqft.net>
Co-authored-by: Yury G. Kudryashov <urkud@urkud.name>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
