fix(QFile): prevent focus on filler input

Author: rstoenescu

ui/src/components/file/QFile.js

@@ -174,7 +174,8 @@ export default Vue.extend({
       return [
         h('input', {
           class: [ this.inputClass, 'q-file__filler' ],
-          style: this.inputStyle
+          style: this.inputStyle,
+          tabindex: -1
         })
       ]
     },