[examples][cli][routing-utils][static-build] replace deprecated String.prototype.substr() (#7588)

.substr() is deprecated so we replace it with .slice() or substring() which aren't deprecated
Signed-off-by: Tobias Speicher <rootcommander@gmail.com>

Co-authored-by: Steven <steven@ceriously.com>

examples/ionic-angular/generate-h2-push.js

@@ -56,7 +56,7 @@ async function main() {
     // if it's an empty string, just ignore it
     if (!formatted) return false;
 
-    let type = url.substr(-3) == 'css' ? 'style' : 'script';
+    let type = url.slice(-3) == 'css' ? 'style' : 'script';
     results += `</${formatted}>;rel=preload;as=${type},`;
 
   });