Add and apply Capybara/RSpec/HaveSelector rule

This rule was added in rubocop-capybara 2.19.0. We were following it
about 85% of the time.

Now we won't have to check both have_css and have_selector when
searching the code.

spec/components/sdg/goals/plain_tag_list_component_spec.rb

@@ -34,7 +34,7 @@ describe SDG::Goals::PlainTagListComponent do
   it "renders icons for each goal" do
     render_inline component
 
-    expect(page).to have_selector ".sdg-goal-icon", count: 2
+    expect(page).to have_css ".sdg-goal-icon", count: 2
   end
 
   it "orders goals by code" do
@@ -48,7 +48,7 @@ describe SDG::Goals::PlainTagListComponent do
 
     render_inline component
 
-    expect(page).to have_selector ".sdg-goal-icon"
+    expect(page).to have_css ".sdg-goal-icon"
     expect(page).to have_link "1+",
                               title: "One more goal",
                               href: "/debates/#{debate.to_param}"

spec/components/sdg/goals/tag_cloud_component_spec.rb

@@ -20,7 +20,7 @@ describe SDG::Goals::TagCloudComponent do
 
     render_inline component
 
-    expect(page).to have_selector ".sdg-goal-icon", count: 17
+    expect(page).to have_css ".sdg-goal-icon", count: 17
     expect(page.first("a")[:title]).to end_with "goal 1"
     expect(page.all("a").last[:title]).to end_with "goal 17"
   end

spec/components/sdg/goals/tag_list_component_spec.rb

@@ -34,7 +34,7 @@ describe SDG::Goals::TagListComponent do
   it "renders links for each goal" do
     render_inline component
 
-    expect(page).to have_selector "a", count: 2
+    expect(page).to have_css "a", count: 2
     expect(page).to have_link "1. No Poverty",
                               title: "See all Debates related to goal 1",
                               href: "/debates?advanced_search#{CGI.escape("[goal]")}=1"
@@ -54,7 +54,7 @@ describe SDG::Goals::TagListComponent do
 
     render_inline component
 
-    expect(page).to have_selector "a", count: 2
+    expect(page).to have_css "a", count: 2
     expect(page).to have_link "1. No Poverty"
     expect(page).to have_link "1+",
                               title: "One more goal",

spec/components/sdg/targets/plain_tag_list_component_spec.rb

@@ -55,7 +55,7 @@ describe SDG::Targets::PlainTagListComponent do
     render_inline component
 
     expect(page).to have_css "li", text: "target 1.1"
-    expect(page).to have_selector "a", count: 1
+    expect(page).to have_css "a", count: 1
     expect(page).to have_link "2+",
                               title: "2 more targets",
                               href: "/debates/#{debate.to_param}"

spec/components/sdg/targets/tag_list_component_spec.rb

@@ -60,7 +60,7 @@ describe SDG::Targets::TagListComponent do
 
     render_inline component
 
-    expect(page).to have_selector "a", count: 2
+    expect(page).to have_css "a", count: 2
     expect(page).to have_link "target 1.1"
     expect(page).to have_link "2+",
                               title: "2 more targets",