feat(geometry/euclidean): circumradius simp lemmas (#3834)
feat(geometry/euclidean): circumradius simp lemmas (#3834)

Mark `dist_circumcenter_eq_circumradius` as a `simp` lemma.  Also add
a variant of that lemma where the distance is the other way round so
`simp` can work with both forms.






leanprover-community/mathlib,leanprover-community/mathlib