Move tests to Core folder and namespace to Terminal.Gui.CoreTests

UnitTests/LineCanvasTests.cs → UnitTests/Core/LineCanvasTests.cs

@@ -2,7 +2,7 @@
 using Xunit;
 using Xunit.Abstractions;
 
-namespace Terminal.Gui.Core {
+namespace Terminal.Gui.CoreTests {
 	public class LineCanvasTests {
 
 		readonly ITestOutputHelper output;