Bundle icons using the Qt resource system.

Simplify resource loading logic and enable reproducible builds.
Fixes #2582

src/core/Bootstrap.cpp

@@ -70,6 +70,7 @@ namespace Bootstrap
 #ifdef QT_NO_DEBUG
         disableCoreDumps();
 #endif
+
         setupSearchPaths();
         applyEarlyQNetworkAccessManagerWorkaround();
         Translator::installTranslators();