feat(Combo): Add support for groupingDirection: none .Remove the sorting of the items when combo has grouping.

[mddragnev]

Closing #1017

[rkaraivanov]

igniteui-webcomponents/src/components/combo/combo.ts

Lines 255 to 261 in 7e541ad

	/**
	* Sorts the items in each group by ascending or descending order.
	* @attr group-sorting
	* @type {"asc" | "desc"}
	*/
	@property({ attribute: 'group-sorting', reflect: false })
	public groupSorting: GroupingDirection = 'asc';

Make sure to add the new member of the groupSorting union.

/**
   * Sorts the items in each group by ascending or descending order.
   * @attr group-sorting
   * @type {"asc" | "desc" | "none"}
   */
  @property({ attribute: 'group-sorting', reflect: false })
  public groupSorting: GroupingDirection = 'asc';