fix: Adds ISpanFormattable to Geometry structs (#1231)

* Adds ISpanFormattable to geometry structs and makes ToString() near-zero-allocation.
* Adds IEquatable, and Parsable to Rectangle3D to get it in-line with the other structs.

Closes #1067

Projects/Server.Tests/Tests/Geometry/WorldLocationTests.cs

@@ -0,0 +1,105 @@
+using System;
+using Xunit;
+
+namespace Server.Tests;
+
+public sealed class WorldLocationTests
+{
+    private static Map CreateMap(string name) => new(0, 0, 0, 1, 1, 0, name, MapRules.Internal);
+
+    private const string _nullMap = "(-null-)";
+
+    private const string _superLongMapName =
+        "Some super long map name that nobody should be using, but probably someone will just because you can!";
+
+    [Fact]
+    public void TestWorldLocationToString()
+    {
+        const string mapName = "Internal Map";
+        var map = CreateMap(mapName);
+
+        const int max = int.MaxValue;
+        const int min = int.MinValue;
+        Assert.Equal($"(0, 0, 0) [{mapName}]", new WorldLocation(0, 0, 0, map).ToString());
+        Assert.Equal($"(1, 1, 1) [{mapName}]", new WorldLocation(1, 1, 1, map).ToString());
+
+        Assert.Equal($"(0, 0, 0) [{_nullMap}]", new WorldLocation(0, 0, 0, null).ToString());
+        Assert.Equal($"(1, 1, 1) [{_nullMap}]", new WorldLocation(1, 1, 1, null).ToString());
+
+        Assert.Equal($"({max}, {max}, {max}) [{mapName}]", new WorldLocation(max, max, max, map).ToString());
+        Assert.Equal($"({min}, {min}, {min}) [{mapName}]", new WorldLocation(min, min, min, map).ToString());
+
+        Assert.Equal($"({max}, {max}, {max}) [{_nullMap}]", new WorldLocation(max, max, max, null).ToString());
+        Assert.Equal($"({min}, {min}, {min}) [{_nullMap}]", new WorldLocation(min, min, min, null).ToString());
+
+        map = CreateMap(_superLongMapName);
+
+        Assert.Equal($"({max}, {max}, {max}) [{_superLongMapName}]", new WorldLocation(max, max, max, map).ToString());
+        Assert.Equal($"({min}, {min}, {min}) [{_superLongMapName}]", new WorldLocation(min, min, min, map).ToString());
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("Internal Map")]
+    [InlineData(_superLongMapName)]
+    public void TestWorldLocationTryFormatSucceeds(string mapName)
+    {
+        var map = mapName != null ? CreateMap(mapName) : null;
+        var mapNameLength = mapName?.Length ?? _nullMap.Length;
+
+        const int max = int.MaxValue;
+        const int min = int.MinValue;
+        char[] array = new char[128];
+
+        var p1 = new WorldLocation(0, 0, 0, map);
+        Assert.True(p1.TryFormat(array, out var cp1, null, null));
+        Assert.Equal(9 + 3 + mapNameLength, cp1);
+        Array.Clear(array);
+
+        var p2 = new WorldLocation(1, 1, 1, map);
+        Assert.True(p2.TryFormat(array, out var cp2, null, null));
+        Assert.Equal(9 + 3 + mapNameLength, cp2);
+        Array.Clear(array);
+
+        array = new char[256]; // We need a bigger buffer!
+        var p3 = new WorldLocation(max, max, max, map);
+        Assert.True(p3.TryFormat(array, out var cp3, null, null));
+        Assert.Equal(9 + 30 + mapNameLength, cp3);
+        Array.Clear(array);
+
+        var p4 = new WorldLocation(min, min, min, map);
+        Assert.True(p4.TryFormat(array, out var cp4, null, null));
+        Assert.Equal(9 + 33 + mapNameLength, cp4);
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("Internal Map")]
+    public void TestWorldLocationTryFormatFails(string mapName)
+    {
+        var map = mapName != null ? CreateMap(mapName) : null;
+
+        const int max = int.MaxValue;
+        const int min = int.MinValue;
+        char[] array = new char[1];
+
+        var p1 = new WorldLocation(0, 0, 0, map);
+        Assert.False(p1.TryFormat(array, out var cp1, null, null));
+        Assert.Equal(0, cp1);
+        Array.Clear(array);
+
+        var p2 = new WorldLocation(1, 1, 1, map);
+        Assert.False(p2.TryFormat(array, out var cp2, null, null));
+        Assert.Equal(0, cp2);
+        Array.Clear(array);
+
+        var p3 = new WorldLocation(max, max, max, map);
+        Assert.False(p3.TryFormat(array, out var cp3, null, null));
+        Assert.Equal(0, cp3);
+        Array.Clear(array);
+
+        var p4 = new WorldLocation(min, min, min, map);
+        Assert.False(p4.TryFormat(array, out var cp4, null, null));
+        Assert.Equal(0, cp4);
+    }
+}