AB axioms in functor categories

This file proves that, when the relevant limits and colimits exist, exactness of limits and colimits carries over from A to the functor category C ⥤ A.

instance CategoryTheory.instHasExactColimitsOfShapeFunctorOfHasFiniteLimits {A : Type u_1} {C : Type u_2} {J : Type u_3} [Category.{v_1, u_1} A] [Category.{v_2, u_2} C] [Category.{v_3, u_3} J] [Limits.HasColimitsOfShape J A] [HasExactColimitsOfShape J A] [Limits.HasFiniteLimits A] : HasExactColimitsOfShape J (Functor C A)

instance CategoryTheory.instHasExactLimitsOfShapeFunctorOfHasFiniteColimits {A : Type u_1} {C : Type u_2} {J : Type u_3} [Category.{v_1, u_1} A] [Category.{v_2, u_2} C] [Category.{v_3, u_3} J] [Limits.HasLimitsOfShape J A] [HasExactLimitsOfShape J A] [Limits.HasFiniteColimits A] : HasExactLimitsOfShape J (Functor C A)