mathlib3

ec1c7d81 - chore(ring_theory/ideal/local_ring): move ring_equiv.local_ring into local_ring.lean (#18686)

chore(ring_theory/ideal/local_ring): move ring_equiv.local_ring into local_ring.lean (#18686) By having `ring_theory.ideal.local_ring` depend on `logic.equiv.transfer_instance`, rather than the other way around, we avoid importing all the dependencies for `local_ring` into files that just need to transfer "elementary" algebraic structures across equivalences. Co-authored-by: Scott Morrison <scott.morrison@gmail.com>