Please consider adding AOT support for .Diff.Compare<T>()

When utilizing libgit2sharp in combination with the .NET 8 PublishAot feature, all repository creation, file staging and committing operations are successful, however, the git diff function throws a NullReferenceException.

Is there a way to get this working under AOT?

Steps To Reproduce:

1. Create a .NET 8 console project

   dotnet new console -o aot-test
   cd aot-test
   

2. Adjust aot-test.csproj to include libgit2sharp reference and activate PublishAot feature

   <Project Sdk="Microsoft.NET.Sdk">
   
     <PropertyGroup>
   	<OutputType>Exe</OutputType>
   	<TargetFramework>net8.0</TargetFramework>
   	<RootNamespace>aot_test</RootNamespace>
   	<ImplicitUsings>enable</ImplicitUsings>
   	<Nullable>enable</Nullable>
   	<PublishAot>true</PublishAot>
     </PropertyGroup>
   
     <ItemGroup>
   	<PackageReference Include="libgit2sharp" Version="0.29.0" />
     </ItemGroup>
   
   </Project>
   

3. Insert the following code into Progmram.cs:

using LibGit2Sharp;

var path = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
Directory.CreateDirectory(path);
Repository.Init(path, false);
var userName = "Tester";
var email = "tester@mail.net";
Func<Signature> getSignature = () => new Signature(userName, email, DateTimeOffset.Now);
using (var repo = new Repository(path))
{
    var fileName = "test.txt";
    var filePath = Path.Combine(path, fileName);
    File.WriteAllText(filePath, "Hello, World!");
    Commands.Stage(repo, fileName);
    var commit1 = repo.Commit("Initial commit", getSignature(), getSignature());
    File.AppendAllText(filePath, "\nAppended Line");
    Commands.Stage(repo, fileName);
    var commit2 = repo.Commit("Second commit", getSignature(), getSignature());
    Console.WriteLine($"Commits Count {repo.Commits.Count()}");
    var changes = repo.Diff.Compare<Patch>(commit1.Tree, commit2.Tree);
    Console.WriteLine($"Diff Changes Count = {changes.Count()}");
}

4. Use dotnet run for testing, it will display:

Commits Count 2
Diff Changes Count = 1

5. Use dotnet publish, .\bin\Release\net8.0\win-x64\publish\aot-test.exe to test the native AOT version, it throws an exception on repo.Diff.Compare<Patch>():

Commits Count 2
Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at aot-test!<BaseAddress>+0x19af4c
   at aot-test!<BaseAddress>+0x199437

Current Behavior:

The native AOT functions for repository creation, file staging, and committing operations are functional, but the git diff function is not.

Anticipated Behavior:

Please consider adding AOT support for the git diff API.

Version of LibGit2Sharp (release number or SHA1)

0.29.0

Operating system(s) tested; .NET runtime tested

• OS: Windows 11
• .NET: 8.0.100

从 .NET 8 控制台项目及其 aot-test.csproj/Program.cs 设置开始，然后使用 dotnet publish 和 repo.Diff.Compare(commit1.Tree, commit2.Tree) 重现故障。原生 AOT 可执行文件完成 diff 调用并报告一个 diff 变更，而不是抛出 NullReferenceException，即表示完成。