feature: add 2 new inputs: disableSorting and disableMultipleSorting

[zvs96]

Need implement 2 new inputs like this.

<div class="example-container">
  <div *ngFor="let item of items"
       ngSortgridItem
       [disableSorting]="false"
       [disableMultipleSorting]="true"
       [ngSortGridItems]="items"
       (sorted)="logger($event)"
  >
    <div class="example-box">{{item}}</div>
  </div>
</div>

[nivekcode]

@zvs96 what would those event do?