feat: port Data.Fintype.Array (#5792)

The dashboard says

> port, but completely rewrite in terms of the new array

However, the new `Array T` isn't finite like `array n T` was, so the rewrite amounts to just deleting everything in the file.



Co-authored-by: Jeremy Tan Jie Rui <reddeloostw@gmail.com>

Mathlib.lean

@@ -1372,6 +1372,7 @@ import Mathlib.Data.Finsupp.Pointwise
 import Mathlib.Data.Finsupp.Pwo
 import Mathlib.Data.Finsupp.ToDfinsupp
 import Mathlib.Data.Finsupp.WellFounded
+import Mathlib.Data.Fintype.Array
 import Mathlib.Data.Fintype.Basic
 import Mathlib.Data.Fintype.BigOperators
 import Mathlib.Data.Fintype.Card

Mathlib/Data/Fintype/Array.lean

@@ -0,0 +1,32 @@
+/-
+Copyright (c) 2017 Mario Carneiro. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mario Carneiro
+
+! This file was ported from Lean 3 source module data.fintype.array
+! leanprover-community/mathlib commit 78314d08d707a6338079f00094bbdb90bf11fc41
+! Please do not edit these lines, except to modify the commit id
+! if you have ported upstream changes.
+-/
+import Mathlib.Data.Fintype.Pi
+import Mathlib.Data.Fintype.Vector
+import Mathlib.Logic.Equiv.Array
+
+/-!
+# `align` information for `Fintype` declarations around mathlib3's `array` (now `Vector`)
+-/
+
+
+variable {α : Type _}
+
+-- porting note: `DArray` does not exist in std4/mathlib4
+-- instance DArray.fintype {n : ℕ} {α : Fin n → Type _} [∀ n, Fintype (α n)] :
+--     Fintype (DArray n α) :=
+--   Fintype.ofEquiv _ (Equiv.dArrayEquivFin _).symm
+#noalign d_array.fintype
+
+-- porting note: The closest thing to `Array' n α` is `Vector n α`, for which we already have this
+-- intance elsewhere.
+-- instance Array'.fintype {n : ℕ} {α : Type _} [Fintype α] : Fintype (Array' n α) :=
+--   DArray.fintype
+#align array.fintype Vector.fintypeₓ