Clean up Widgets

* Move /Widgets/Live/* to /Live/*
* Move /Widgets/Prompt/* to /Prompts/*
* Move tests and expectations to match the new locations

test/Spectre.Console.Tests/Unit/Live/Progress/DownloadedColumnTests.cs

@@ -0,0 +1,30 @@
+using System.Globalization;
+using Shouldly;
+using Xunit;
+
+namespace Spectre.Console.Tests.Unit
+{
+    public sealed class DownloadedColumnTests
+    {
+        [Theory]
+        [InlineData(0, 1, "0/1 byte")]
+        [InlineData(37, 101, "37/101 bytes")]
+        [InlineData(101, 101, "101 bytes")]
+        [InlineData(512, 1024, "0.5/1.0 KB")]
+        [InlineData(1024, 1024, "1.0 KB")]
+        [InlineData(1024 * 512, 5 * 1024 * 1024, "0.5/5.0 MB")]
+        [InlineData(5 * 1024 * 1024, 5 * 1024 * 1024, "5.0 MB")]
+        public void Should_Return_Correct_Value(double value, double total, string expected)
+        {
+            // Given
+            var fixture = new ProgressColumnFixture<DownloadedColumn>(value, total);
+            fixture.Column.Culture = CultureInfo.InvariantCulture;
+
+            // When
+            var result = fixture.Render();
+
+            // Then
+            result.ShouldBe(expected);
+        }
+    }
+}