Smoke test for tiling

tests/ImageSharp.Tests/Formats/Heif/Av1/Av1TilingTests.cs

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+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Heif.Av1;
+using SixLabors.ImageSharp.Formats.Heif.Av1.OpenBitstreamUnit;
+using SixLabors.ImageSharp.Formats.Heif.Av1.Symbol;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Heif.Av1;
+
+[Trait("Format", "Avif")]
+public class Av1TilingTests
+{
+    // [Theory]
+    [InlineData(TestImages.Heif.XnConvert, 0x010E, 0x03CC, 18, 0x03CC - 18)]
+    public void ReadFirstTile(string filename, int headerOffset, int headerSize, int tileOffset, int tileSize)
+    {
+        // Assign
+        string filePath = Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, filename);
+        byte[] content = File.ReadAllBytes(filePath);
+        Span<byte> headerSpan = content.AsSpan(headerOffset, headerSize);
+        Span<byte> tileSpan = content.AsSpan(tileOffset, tileSize);
+        Av1BitStreamReader reader = new(headerSpan);
+        IAv1TileDecoder stub = new Av1TileDecoderStub();
+        ObuReader obuReader = new();
+        obuReader.Read(ref reader, headerSize, stub);
+        Av1TileDecoder decoder = new(obuReader.SequenceHeader, obuReader.FrameHeader);
+
+        // Act
+        decoder.DecodeTile(tileSpan, 0);
+
+        // Assert
+    }
+}