Fix not auto-corrected for Rails/DuplicateAssociation

This PR is fixed not auto-corrected case for `Rails/DuplicateAssociation`

The following problems that could'nt be corrected automatically
when exactly the same association was defined have been resolved.

```ruby
class Post < ApplicationRecord
  belongs_to :foo
  belongs_to :bar
  belongs_to :foo
end
```

changelog/fix_not_autocrrected_for_rails_duplicate_association.md

@@ -0,0 +1 @@
+* [#703](https://github.com/rubocop/rubocop-rails/pull/703): Fix not auto-corrected for `Rails/DuplicateAssociation`. ([@ydah][])

lib/rubocop/cop/rails/duplicate_association.rb

@@ -35,7 +35,7 @@ def on_class(class_node)
           offenses(class_node).each do |name, nodes|
             nodes.each do |node|
               add_offense(node, message: format(MSG, name: name)) do |corrector|
-                next if nodes.last == node
+                next if same_line?(nodes.last, node)
 
                 corrector.remove(range_by_whole_lines(node.source_range, include_final_newline: true))
               end

spec/rubocop/cop/rails/duplicate_association_spec.rb

@@ -3,6 +3,27 @@
 RSpec.describe RuboCop::Cop::Rails::DuplicateAssociation, :config do
   describe 'belongs_to' do
     it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        class Post < ApplicationRecord
+          belongs_to :foo
+          ^^^^^^^^^^^^^^^ Association `foo` is defined multiple times. Don't repeat associations.
+          belongs_to :bar
+          belongs_to :foo
+          ^^^^^^^^^^^^^^^ Association `foo` is defined multiple times. Don't repeat associations.
+          belongs_to :blah
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        class Post < ApplicationRecord
+          belongs_to :bar
+          belongs_to :foo
+          belongs_to :blah
+        end
+      RUBY
+    end
+
+    it 'registers an offense with scope block' do
       expect_offense(<<~RUBY)
         class Post < ApplicationRecord
           belongs_to :foo
@@ -26,6 +47,27 @@ class Post < ApplicationRecord
 
   describe 'has_many' do
     it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        class Post < ApplicationRecord
+          has_many :foos
+          ^^^^^^^^^^^^^^ Association `foos` is defined multiple times. Don't repeat associations.
+          has_many :bars
+          has_many :foos
+          ^^^^^^^^^^^^^^ Association `foos` is defined multiple times. Don't repeat associations.
+          has_many :blahs
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        class Post < ApplicationRecord
+          has_many :bars
+          has_many :foos
+          has_many :blahs
+        end
+      RUBY
+    end
+
+    it 'registers an offense with scope block' do
       expect_offense(<<~RUBY)
         class Post < ApplicationRecord
           has_many :foos
@@ -49,6 +91,27 @@ class Post < ApplicationRecord
 
   describe 'has_one' do
     it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        class Post < ApplicationRecord
+          has_one :foo
+          ^^^^^^^^^^^^ Association `foo` is defined multiple times. Don't repeat associations.
+          has_one :bar
+          has_one :foo
+          ^^^^^^^^^^^^ Association `foo` is defined multiple times. Don't repeat associations.
+          has_one :blah
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        class Post < ApplicationRecord
+          has_one :bar
+          has_one :foo
+          has_one :blah
+        end
+      RUBY
+    end
+
+    it 'registers an offense with scope block' do
       expect_offense(<<~RUBY)
         class Post < ApplicationRecord
           has_one :foo
@@ -72,6 +135,27 @@ class Post < ApplicationRecord
 
   describe 'has_and_belongs_to_many' do
     it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        class Post < ApplicationRecord
+          has_and_belongs_to_many :foos
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Association `foos` is defined multiple times. Don't repeat associations.
+          has_and_belongs_to_many :bars
+          has_and_belongs_to_many :foos
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Association `foos` is defined multiple times. Don't repeat associations.
+          has_and_belongs_to_many :blahs
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        class Post < ApplicationRecord
+          has_and_belongs_to_many :bars
+          has_and_belongs_to_many :foos
+          has_and_belongs_to_many :blahs
+        end
+      RUBY
+    end
+
+    it 'registers an offense with scope block' do
       expect_offense(<<~RUBY)
         class Post < ApplicationRecord
           has_and_belongs_to_many :foos