[NUI] Open new GridLayout APIs and Properties (#1834)

[NUI] Open new GridLayout APIs and Properties (#1834)

GridLayout.Orientation
 Horizontal
 Vertical

GridLayout.StretchFlags
 None = 0
 Fill = 1
 Expand = 2
 ExpandAndFill = Fill + Expand

GridLayout.Alignment
Start = 0
Center = 1
End = 2
static int GetColumn(View view)
static int GetColumnSpan(View view)
static int GetRow(View view)
static int GetRowSpan(View view)
static StretchFlags GetHorizontalStretch(View view)
static StretchFlags GetVerticalStretch(View view)
static StretchFlags GetHorizontalAlignment(View view)
static StretchFlags GetVerticalAlignment(View view)
static void SetColumn(View view, int value)
static void SetColumnSpan(View view, int value)
static void SetRow(View view, int value)
static void SetRowSpan(View view, int value)
static void SetHorizontalStretch(View view, StretchFlags value)
static void SetVerticalStretch(View view, StretchFlags value)
static void SetHorizontalAlignment(View view, Alignment value)
static void SetVerticalAlignment(View view, Alignment value)

float ColumnSpacing { get; set; }
float RowSpacing { get; set; }
GridLayout.Orientation GridOrientation { get; set; }
int Rows { get; set; }
int Columns{ get; set; }