Add rubocop spacing rules

We were following these rules in most places; we just didn't define them
anywhere.

spec/features/moderation/budget_investments_spec.rb

@@ -15,7 +15,7 @@ describe "Moderate budget investments" do
     Setting["process.budgets"] = nil
     login_as(@mod.user)
 
-    expect{ visit moderation_budget_investments_path }.to raise_exception(FeatureFlags::FeatureDisabled)
+    expect { visit moderation_budget_investments_path }.to raise_exception(FeatureFlags::FeatureDisabled)
   end
 
   scenario "Hiding an investment", :js do

spec/features/moderation/debates_spec.rb

@@ -7,7 +7,7 @@ describe "Moderate debates" do
     moderator = create(:moderator)
     login_as(moderator.user)
 
-    expect{ visit moderation_debates_path }.to raise_exception(FeatureFlags::FeatureDisabled)
+    expect { visit moderation_debates_path }.to raise_exception(FeatureFlags::FeatureDisabled)
   end
 
   scenario "Hide", :js do

spec/features/moderation/proposals_spec.rb

@@ -7,7 +7,7 @@ describe "Moderate proposals" do
     moderator = create(:moderator)
     login_as(moderator.user)
 
-    expect{ visit moderation_proposals_path }.to raise_exception(FeatureFlags::FeatureDisabled)
+    expect { visit moderation_proposals_path }.to raise_exception(FeatureFlags::FeatureDisabled)
   end
 
   scenario "Hide", :js do