Feature/block page until loaded (#152)

* Added DIV and script to block page until DOM is loaded.
Not working yet, DIV is not found in script.

* bugfix loader animation shown while readyState != 'complete'

* - loader is now started onbeforeunload.
- to have less screen flickering body part is static instead of hidden

* Renamed negotiator.css to force reload of CSS in browser

* removed unwanted characters from merging

Co-authored-by: Emilian Jungwirth <emilian.jung+github@gmail.com>
Co-authored-by: jungwire <88881847+jungwire@users.noreply.github.com>

src/main/webapp/components/styles.xhtml

@@ -20,7 +20,7 @@
 
     <h:outputStylesheet name="css/bbmri.css" />
     <h:outputStylesheet name="css/buttons.css" />
-    <h:outputStylesheet name="css/negotiator.css" />
+    <h:outputStylesheet name="css/negotiator20221019.css" />
 
 
     <h:outputScript library="webjars" name="jquery/3.3.1/jquery.min.js" />
@@ -72,4 +72,4 @@
         };
 
     </h:outputScript>
-</ui:composition>
+</ui:composition>