message: fix: show custom-ui spinner on top of schema forms
diff: <i class="fa fa-cog fa-spin" style="font-size: 72px;"></i>
  </div>
  - <div *ngIf="pluginSpinner"
  - class="loading-overlay text-center primary-text d-flex align-items-center justify-content-center">
  - <i class="fa fa-cog fa-spin" style="font-size: 72px;"></i>
  - </div>
  -
  <iframe width="100%" height="1px;" #custompluginui
  sandbox="allow-same-origin allow-scripts allow-popups allow-popups-to-escape-sandbox allow-downloads allow-forms"
  style="border: 0;">
  </button>
  </div>
  </div>
  +
  + <div *ngIf="pluginSpinner"
  + class="loading-overlay text-center primary-text d-flex align-items-center justify-content-center">
  + <i class="fa fa-cog fa-spin" style="font-size: 72px;"></i>
  + </div>
  </div>
  <div class="modal-footer justify-content-between">
  