Don’t allow paragraphs without class attribute

All paragraphs should have class="govuk-body", or be otherwise
custom-styled. This commit adds some extra checks to our test fixture
that looks for paragraphs that don’t have any styling. Our test coverage
is pretty good, so this should check almost all pages, and prevent
regressions.

I’ve done this in such a way that it can be extended for other elements
(e.g. links) in the future.

app/templates/views/organisations/add-nhs-local-organisation.html

@@ -16,7 +16,7 @@
     back_link=url_for('main.request_to_go_live', service_id=current_service.id)
   ) }}
   {% call form_wrapper() %}
-    <p>
+    <p class="govuk-body">
       {{ form.organisations.label.text }}
     </p>
     {{ live_search(target_selector='.multiple-choice', show=True, form=search_form, label='Search by name') }}

app/templates/views/organisations/organisation/settings/edit-domains.html

@@ -17,7 +17,7 @@
   ) }}
   <div class="govuk-grid-row">
     <div class="govuk-grid-column-five-sixths">
-      <p>
+      <p class="govuk-body">
         If a user’s email addresses ends with one of these domains then
         any services they create will be associated with this organisation.
       </p>

app/templates/views/organisations/organisation/settings/edit-go-live-notes.html

@@ -16,7 +16,7 @@
   ) }}
   <div class="govuk-grid-row">
     <div class="govuk-grid-column-five-sixths">
-      <p>
+      <p class="govuk-body">
         Text entered here will be displayed in the Zendesk ticket when a service
         belonging to this organisation requests to go live.
       </p>

app/templates/views/organisations/organisation/settings/edit-name/confirm.html

@@ -20,7 +20,7 @@
 
     {% call form_wrapper() %}
       {{ textbox(form.password, autocomplete='current-password') }}
-      <p> Your organisation name will be changed from {{ current_org.name }} to {{ new_name }} </p>
+      <p class="govuk-body"> Your organisation name will be changed from {{ current_org.name }} to {{ new_name }} </p>
       {{ page_footer('Confirm') }}
     {% endcall %}
     </div>

app/templates/views/organisations/organisation/users/user/index.html

@@ -15,7 +15,7 @@
     back_link=url_for('.manage_org_users', org_id=current_org.id)
   ) }}
 
-  <p>
+  <p class="govuk-body">
     {{ user.email_address }}
   </p>