chore: reduce imports in several files (#14919)

Found by using the output of #14840.

Author: adomani

Mathlib/Algebra/Group/Action/Defs.lean

@@ -7,8 +7,6 @@ import Mathlib.Algebra.Group.Commute.Defs
 import Mathlib.Algebra.Group.TypeTags
 import Mathlib.Algebra.Opposites
 import Mathlib.Logic.Embedding.Basic
-import Mathlib.Logic.Function.Iterate
-import Mathlib.Tactic.Common
 
 /-!
 # Definitions of group actions

Mathlib/Algebra/GroupWithZero/WithZero.lean

@@ -3,7 +3,6 @@ Copyright (c) 2018 Mario Carneiro. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Mario Carneiro, Johan Commelin
 -/
-import Mathlib.Algebra.Group.Equiv.Basic
 import Mathlib.Algebra.Group.WithOne.Defs
 import Mathlib.Algebra.GroupWithZero.Hom
 import Mathlib.Algebra.GroupWithZero.Units.Basic

Mathlib/Algebra/Order/Interval/Set/Group.lean

@@ -5,7 +5,6 @@ Authors: Johannes Hölzl, Mario Carneiro, Patrick Massot, Yury Kudryashov, Rémy
 -/
 import Mathlib.Algebra.Order.Group.Abs
 import Mathlib.Algebra.Order.Group.Basic
-import Mathlib.Algebra.Order.Group.OrderIso
 import Mathlib.Algebra.Order.Ring.Defs
 import Mathlib.Data.Int.Cast.Lemmas
 import Mathlib.Order.Interval.Set.Basic

Mathlib/Data/Int/Cast/Lemmas.lean

@@ -5,8 +5,6 @@ Authors: Mario Carneiro
 -/
 import Mathlib.Algebra.Ring.Hom.Basic
 import Mathlib.Algebra.Ring.Int
-import Mathlib.Data.Nat.Cast.Basic
-import Mathlib.Data.Nat.Cast.Commute
 
 /-!
 # Cast of integers (additional theorems)

Mathlib/Data/Nat/Cast/Basic.lean

@@ -4,8 +4,6 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Mario Carneiro
 -/
 import Mathlib.Algebra.Divisibility.Basic
-import Mathlib.Algebra.Group.Equiv.Basic
-import Mathlib.Algebra.Group.TypeTags
 import Mathlib.Algebra.Ring.Hom.Defs
 import Mathlib.Algebra.Ring.Nat
 

Mathlib/Data/Nat/Cast/Order/Basic.lean

@@ -4,7 +4,6 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Mario Carneiro
 -/
 import Mathlib.Data.Nat.Cast.Basic
-import Mathlib.Algebra.CharZero.Defs
 import Mathlib.Algebra.Order.Monoid.Unbundled.Basic
 import Mathlib.Data.Nat.Cast.NeZero
 import Mathlib.Algebra.Order.ZeroLEOne

Mathlib/Data/Set/Pairwise/Basic.lean

@@ -4,7 +4,6 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johannes Hölzl
 -/
 import Mathlib.Data.Set.Function
-import Mathlib.Logic.Relation
 import Mathlib.Logic.Pairwise
 
 /-!

Mathlib/Tactic/CategoryTheory/Reassoc.lean

@@ -5,7 +5,6 @@ Authors: Scott Morrison
 -/
 import Mathlib.CategoryTheory.Functor.Basic
 import Mathlib.Util.AddRelatedDecl
-import Mathlib.Lean.Meta.Simp
 
 /-!
 # The `reassoc` attribute