Add column header sorting to KendoGrid

[YevgeniyShunevych]

• Add KendoGridHeaderSortOrder enum with values: None, Ascending and Descending.

• Add KendoGridHeader<TOwner> control inherited from TableHeader<TOwner> with members:

  public Text<TOwner> Text { get; }
  
  public DataProvider<KendoGridHeaderSortOrder, TOwner> SortOrder { get; }
  
  public TOwner SortAscending();
  
  public TOwner SortDescending();
  
  TOwner Sort(KendoGridHeaderSortOrder sortOrder);

• Update KendoGrid classes to use KendoGridHeader<TOwner> by default as column header type.