Indexing a tree by path yields different result with trailing slash

When a slash is included when indexing into a tree to a subtree, the resulting TreeEntry has a path with a duplicated last path part.

using System.Text;
using LibGit2Sharp;

var path = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());

using var repo = new Repository(Repository.Init(path, isBare: true));

var bytes = Encoding.UTF8.GetBytes("Hello, World!");

var blob = repo.ObjectDatabase.CreateBlob(new MemoryStream(bytes));

var td = new TreeDefinition();
td.Add("some/deeply/nested/file", blob, Mode.NonExecutableFile);

var tree = repo.ObjectDatabase.CreateTree(td);

var withSlash = tree["some/deeply/"].Path;
var withoutSlash = tree["some/deeply"].Path;

Console.WriteLine(withSlash);       // some/deeply/deeply
Console.WriteLine(withoutSlash);    // some/deeply

I was seeing this across Linux and Windows, on versions 0.31 and 0.32 and .NET 10 and Framework 4.8

使用提供的 TreeDefinition 和树索引器示例重现这一差异，比较针对 "some/deeply/" 和 "some/deeply" 返回的路径。跟踪已索引子树的 TreeEntry 路径构造，并添加一个覆盖这两个输入的回归测试。当带尾部斜杠的索引返回与不带斜杠的等效路径相同的非重复路径时，即表示完成。