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.

tests/app/main/views/organisations/test_organisation_invites.py

@@ -80,7 +80,7 @@ def test_invite_org_user_errors_when_same_email_as_inviter(
     )
 
     assert mock_invite_org_user.called is False
-    assert normalize_spaces(page.select_one('.error-message').text) == 'You cannot send an invitation to yourself'
+    assert 'You cannot send an invitation to yourself' in normalize_spaces(page.select_one('.govuk-error-message').text)
 
 
 def test_accepted_invite_when_other_user_already_logged_in(