Move remaining text into locale file

Moves the title, timestamp and reference text into the locale file.

Also replaces the quotes around the form title with curly quotes.

app/views/aws_ses_form_submission_mailer/submission_email.html.erb

@@ -1,11 +1,11 @@
 <p>
-  This is a completed "<%= @mailer_options.title %>" form.
+  <%= I18n.t("mailer.submission.title", title: @mailer_options.title) %>
 </p>
 <p>
-  This form was submitted at <%= @mailer_options.timestamp.strftime("%l:%M%P").strip %> on <%= @mailer_options.timestamp.strftime("%-d %B %Y") %>
+  <%= I18n.t("mailer.submission.time", time: @mailer_options.timestamp.strftime("%l:%M%P").strip, date: @mailer_options.timestamp.strftime("%-d %B %Y") ) %>
 </p>
 <p>
-  GOV.​UK Forms reference number: <%= @mailer_options.submission_reference %><br>
+  <%= I18n.t("mailer.submission.reference", submission_reference: @mailer_options.submission_reference) %>
 </p>
 <p style="margin: 0 0 20px 0; border-left: 10px solid #B1B4B6; padding: 15px;">
   <%= I18n.t("mailer.submission.check_before_using") %>

config/locales/en.yml

@@ -199,7 +199,10 @@ en:
       check_before_using: Check that this data looks safe before you use it
       file_attached: "%{filename} (attached to this email)"
       from: GOV.UK Forms <%{email_address}>
+      reference: 'GOV.​UK Forms reference number: %{submission_reference}'
       subject: 'Form submission: %{form_title} - reference: %{reference}'
+      time: This form was submitted at %{time} on %{date}
+      title: This is a completed “%{title}” form.
   mode:
     phase_banner_tag_preview-archived: Archived preview
     phase_banner_tag_preview-draft: Draft preview

spec/mailers/aws_ses_form_submission_mailer_spec.rb

@@ -34,8 +34,16 @@
       expect(mail.body).to match(answer_content)
     end
 
+    it "includes the form title text" do
+      expect(mail.body).to have_css("p", text: I18n.t("mailer.submission.title", title:))
+    end
+
+    it "includes text about the submission time" do
+      expect(mail.body).to have_css("p", text: I18n.t("mailer.submission.time", time: submission_timestamp.strftime("%l:%M%P").strip, date: submission_timestamp.strftime("%-d %B %Y")))
+    end
+
     it "includes the submission reference" do
-      expect(mail.body).to match("reference number: #{submission_reference}")
+      expect(mail.body).to have_css("p", text: I18n.t("mailer.submission.reference", submission_reference:))
     end
 
     it "includes text about checking the answers" do