Convert EmailFields to GovukEmailFields

Changes those fields (and sometimes also regular text input fields)
 in the following forms:
- LoginForm
- RegisterUserForm
- ChangeEmailForm
- FeedbackOrProblem
- AcceptAgreementForm
- ChangeNameForm (only name field here, but used in the same template
field as ChangeEmailForm here: app/templates/views/user-profile/change.html)

Also includes changes to templates that use this form
and associated tests.

app/templates/views/service-settings/email-reply-to/edit.html

@@ -16,11 +16,12 @@
     back_link=url_for('main.service_email_reply_to', service_id=current_service.id)
   ) }}
   {% call form_wrapper() %}
-    {{ textbox(
-      form.email_address,
-      width='1-1',
-      safe_error_message=True,
-      hint='This should be a shared inbox managed by your team, not your own email address.'
+    {{ form.email_address(
+        param_extensions={
+          "hint": {"text": "This should be a shared inbox managed by your team, not your own email address"},
+          "classes": "govuk-!-width-full"
+        },
+        error_message_with_html=True
     ) }}
     {% if form.is_default.data %}
       <p class="form-group">