feat(ring_theory/ideal/local_ring): Isomorphisms are local (#8850)
feat(ring_theory/ideal/local_ring): Isomorphisms are local (#8850)

Adds the fact that isomorphisms (and ring equivs) are local ring homomorphisms.



Co-authored-by: Johan Commelin <759412786bc533369b22377bf83fb9056c5b25b2@commelin.net>

leanprover-community/mathlib,leanprover-community/mathlib