Move the product instances into its own file

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

Equivalence.agda

@@ -9,29 +9,3 @@ record IsEquivalence {a} (A : Set a) (_≈_ : A → A → Set a) : Set a where
         ≈-refl : {a : A} → a ≈ a
         ≈-sym : {a b : A} → a ≈ b → b ≈ a
         ≈-trans : {a b c : A} → a ≈ b → b ≈ c → a ≈ c
-
-module IsEquivalenceInstances where
-    module ForProd {a} {A B : Set a}
-        (_≈₁_ : A → A → Set a) (_≈₂_ : B → B → Set a)
-        (eA : IsEquivalence A _≈₁_) (eB : IsEquivalence B _≈₂_) where
-
-        infix 4 _≈_
-
-        _≈_ : A × B → A × B → Set a
-        (a₁ , b₁) ≈ (a₂ , b₂) = (a₁ ≈₁ a₂) × (b₁ ≈₂ b₂)
-
-        ProdEquivalence : IsEquivalence (A × B) _≈_
-        ProdEquivalence = record
-            { ≈-refl = λ {p} →
-                ( IsEquivalence.≈-refl eA
-                , IsEquivalence.≈-refl eB
-                )
-            ; ≈-sym = λ {p₁} {p₂} (a₁≈a₂ , b₁≈b₂) →
-                ( IsEquivalence.≈-sym eA a₁≈a₂
-                , IsEquivalence.≈-sym eB b₁≈b₂
-                )
-            ; ≈-trans = λ {p₁} {p₂} {p₃} (a₁≈a₂ , b₁≈b₂) (a₂≈a₃ , b₂≈b₃) →
-                ( IsEquivalence.≈-trans eA a₁≈a₂ a₂≈a₃
-                , IsEquivalence.≈-trans eB b₁≈b₂ b₂≈b₃
-                )
-            }