Grid: Provide information for the actual height of RowDefinition and actual width of ColumnDefinition

[eli-popova]

Description

Currently, we can set the Height property of a RowDefinition object and the Width property of a ColumnDefinition object with some value and a unit type of Absolute, Star and Auto. What we need, however, is to have information about the real sizes of rows/columns in the grid after it has been measured. In WinUI and WPF we have a public API providing such information. It would be great if we had this in MAUI as well.

Public API Changes

public sealed class RowDefinition
{
   ...
   public double ActualHeight { get; private set; }   ---> the calculated height of the row after the grid has been measured and arranged
   ...
}

public sealed class ColumnDefinition
{
    ...
    public double ActualWidth { get; private set;}    ---> the calculated width of the column after the grid has been measured and arranged
    ...
}

Intended Use-Case

We need this information as we are developing a GridSplitter control. To resize rows/columns by dragging the splitter we need to know their exact sizes.