[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/admin/index.html

@@ -164,5 +164,5 @@
   </q-card>
 </q-dialog>
 {% endblock %} {% block scripts %} {{ window_vars(user) }}
-<script src="/static/js/admin.js"></script>
+<script src="{{ static_url_for('static', 'js/admin.js') }}"></script>
 {% endblock %}