Move ‘new thing’ buttons alongside heading

On the send messages and manage team pages we have big green buttons for
adding/inviting a new template or team member.

On the add template page it was at the bottom, and often got missed.

On the manage team page it was at the top, but maybe too prominent because it’s
big and green.

This commit tries putting it in the top right of the page instead (except when
the template page is empty, in which case it’s unchanged).

tests/app/main/views/test_manage_users.py

@@ -123,7 +123,7 @@ def test_should_show_page_for_inviting_user(
             client.login(api_user_active)
             response = client.get(url_for('main.invite_user', service_id=55555))
 
-        assert 'Add a new team member' in response.get_data(as_text=True)
+        assert 'Invite a team member' in response.get_data(as_text=True)
         assert response.status_code == 200
 
 
@@ -277,6 +277,6 @@ def test_user_cant_invite_themselves(
 
         assert response.status_code == 200
         page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
-        assert page.h1.string.strip() == 'Add a new team member'
+        assert page.h1.string.strip() == 'Invite a team member'
         form_error = page.find('span', class_='error-message').string.strip()
         assert form_error == "You can't send an invitation to yourself"