Added Circles and Polygons to Maps

[edburley]

Circle and Polygon drawing was missing from CommunityToolkit.Maui.Maps/Handler/Map/MapHandler.Windows.cs.

This patch adds both Circles and Polygons.
The erase method for pins had to be modified to not clear things that aren't pins.

Usage:
MyMap.MapElements.Clear();
Circle circle = new Circle
{
Center = center,
Radius = Distance.FromMiles(circleRadius),
StrokeColor = Color.FromArgb("#88FF0000"),
StrokeWidth = 3,
FillColor = Color.FromArgb("#88FFC0CB")
};
MyMap.MapElements.Add(circle);

0001-MapHandler-Windows-cs.patch

[CliffAgius]

Closing as this is now implemented you can read the docs here:

https://learn.microsoft.com/en-us/dotnet/maui/user-interface/controls/map?view=net-maui-8.0#polygons-polylines-and-circles