feat(ring_theory/rees_algebra): Define the Rees algebra of an ideal. (#15089)
feat(ring_theory/rees_algebra): Define the Rees algebra of an ideal. (#15089)




Co-authored-by: Andrew Yang <5a6b17dbbc661dec6b250b080ab0033de7d56af5@users.noreply.github.com>

leanprover-community/mathlib,leanprover-community/mathlib