Color: add overloads so int does not get clamped like a float

[swharden]

This PR adds overloads for the Color constructor, FromRgb(), and FromRgba() that accept int.

Reported by @PureWeen in #253 and @davidbritch in #308, there exists a problem where int values (expected to be 0-255) are interpreted as float and clamped between 0 and 1.0, demonstrated here:

// fill a circle with a random color using a fluent method
canvas.FillColor = Color.FromRgba(rand.Next(0, 255), rand.Next(0, 255), rand.Next(0, 255), rand.Next(100, 200));
canvas.FillCircle(pt1, radius);

// fill a circle with a random color using a constructor
canvas.FillColor = new Color(rand.Next(0, 255), rand.Next(0, 255), rand.Next(0, 255), rand.Next(100, 200));
canvas.FillCircle(pt2, radius);

Full source code

using Microsoft.Maui.Graphics;
using Microsoft.Maui.Graphics.Skia;

Random rand = new(0);
using BitmapExportContext bmp = new SkiaBitmapExportContext(300, 200, 1.0f);
ICanvas canvas = bmp.Canvas;

// draw a test pattern in the background
canvas.FillColor = Colors.DarkGray;
canvas.FillRectangle(0, 0, bmp.Width, bmp.Height);
canvas.StrokeSize = 3;
canvas.StrokeColor = Colors.Black;
for (int i = 0; i < bmp.Width * 2; i += 50)
    canvas.DrawLine(0, i, i, 0);

// define a pair of circles
PointF pt1 = new(100, 100);
PointF pt2 = new(200, 100);
float radius = 75;

// fill a circle with a random color using a fluent method
canvas.FillColor = Color.FromRgba(rand.Next(0, 255), rand.Next(0, 255), rand.Next(0, 255), rand.Next(100, 200));
canvas.FillCircle(pt1, radius);

// fill a circle with a random color using a constructor
canvas.FillColor = new Color(rand.Next(0, 255), rand.Next(0, 255), rand.Next(0, 255), rand.Next(100, 200));
canvas.FillCircle(pt2, radius);

string filePath = Path.GetFullPath("test.png");
using FileStream fs = new(filePath, FileMode.Create);
bmp.WriteToStream(fs);
Console.WriteLine(filePath);

Original Behavior	New Behavior