Use Capybara methods to find/click/check links

We applied the Capybara/SpecificMatcher in commit f52a86b46.  However,
this rule doesn't convert methods finding <a> tags to methods finding
links because <a> tags only count as links when they've got the `href`
attribute. For instance, in the `xss_spec.rb` file we check what happens
when clicking on an anchor tag because we're testing that the `href`
attribute has been removed and so we can't use `click_link`.

So, basically, we can't enable a rule to automatically detect when we're
using `have_css` instead of `have_link`, but we should still do it
because `have_link` adds an extra check which affects accessibility
since it makes sure the tag has the `href` attribute and so it's
recognizable as a link by screen readers.

spec/components/sdg_management/menu_component_spec.rb

@@ -39,7 +39,7 @@ describe SDGManagement::MenuComponent do
     it "does not generate links to any processes" do
       render_inline component
 
-      expect(page).to have_css "a", count: 2
+      expect(page).to have_link count: 2
       expect(page).to have_link "Goals and Targets"
       expect(page).to have_link "SDG homepage"
     end
@@ -57,7 +57,7 @@ describe SDGManagement::MenuComponent do
     it "does not generate links to any processes" do
       render_inline component
 
-      expect(page).to have_css "a", count: 2
+      expect(page).to have_link count: 2
       expect(page).to have_link "Goals and Targets"
       expect(page).to have_link "SDG homepage"
     end