[FEAT] add cache busting via static_url_for and settings.cache_version (#1964)

closes #1954
this PR add cache busting to `/static`
additionally i combined `lnbits/core/static` with `lnbits/static`, it was not necessary and added a lot of duplicate code for cache busting. now you have to include all static files inside the html files with `{{ static_url_for("static", "app.css" ) }}`

Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>
Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

lnbits/core/templates/node/public.html

@@ -51,7 +51,7 @@ context %} {% block page %}
 </div>
 
 {% endblock %} {% block scripts %} {{ window_vars(user) }}
-<script src="/core/static/js/node.js"></script>
+<script src="{{ static_url_for('static', 'js/node.js') }}"></script>
 <script>
   Vue.component(VueQrcode.name, VueQrcode)
   Vue.use(VueQrcodeReader)