Add gl_tab_counter_badge helper

This helper creates a badge element
to be used in GlTabs.

app/helpers/tab_helper.rb

@@ -210,3 +210,10 @@ module TabHelper
     current_page?(options)
   end
 end
+
+def gl_tab_counter_badge(count)
+  content_tag(:span,
+    count,
+    class: 'badge badge-muted badge-pill gl-badge sm gl-tab-counter-badge'
+  )
+end
\ No newline at end of file

spec/helpers/tab_helper_spec.rb

@@ -150,4 +150,10 @@ RSpec.describe TabHelper do
       end
     end
   end
+
+  describe 'gl_tab_counter_badge' do
+    it 'creates a tab counter badge' do
+      expect(gl_tab_counter_badge(1)).to eq('<span class="badge badge-muted badge-pill gl-badge sm gl-tab-counter-badge">1</span>')
+    end
+  end
 end