Change table dropdown text

- to match designs, and make it more readable
- also add this to a test

config/locales/en.yml

@@ -33,7 +33,7 @@ en:
         characters: characters
         words: words
     chart:
-      table_dropdown: Data table
+      table_dropdown: View data as a table
       accessibility_html: This chart is a visual representation of the data available in the table.
       accessibility_link: Skip to "%{chart_heading}" data table
       accessibility_heading: Data table for "%{chart_heading}"

spec/components/chart_spec.rb

@@ -41,6 +41,7 @@ def component_name
   it "renders when given valid data" do
     render_component(data)
     assert_select '.gem-c-chart.govuk-\!-margin-bottom-3', 1
+    assert_select ".govuk-details__summary-text", text: "View data as a table"
   end
 
   it "renders the correct table data horizontally" do