CE port of "Move merge request approval settings"

This is for the upcoming feature for MR approval rules (https://gitlab.com/gitlab-org/gitlab-ee/issues/1979)

app/views/projects/edit.html.haml

@@ -95,6 +95,8 @@
         = render 'projects/merge_request_settings', form: f
         = f.submit 'Save changes', class: "btn btn-success qa-save-merge-request-changes"
+  = render_if_exists 'projects/merge_request_approvals_settings', expanded: expanded
+
   = render_if_exists 'projects/service_desk_settings'
   %section.settings.no-animate{ class: ('expanded' if expanded) }

spec/features/projects/settings/user_manages_merge_requests_settings_spec.rb

@@ -10,19 +10,19 @@ describe 'Projects > Settings > User manages merge request settings' do
   end
   it 'shows "Merge commit" strategy' do
-    page.within '.merge-requests-feature' do
+    page.within '#js-merge-request-settings' do
       expect(page).to have_content 'Merge commit'
     end
   end
   it 'shows "Merge commit with semi-linear history " strategy' do
-    page.within '.merge-requests-feature' do
+    page.within '#js-merge-request-settings' do
       expect(page).to have_content 'Merge commit with semi-linear history'
     end
   end
   it 'shows "Fast-forward merge" strategy' do
-    page.within '.merge-requests-feature' do
+    page.within '#js-merge-request-settings' do
       expect(page).to have_content 'Fast-forward merge'
     end
   end