Feature request: Create blobs in-memory

I would like to make a diff between two strings with libgit2sharp. The strings hold file contents loaded elsewhere. The diff.Compare-methods only take blobs, and the constructors of the Blobclass don't accept strings or streams and are marked internal. This prevents me from creating blobs directly. I have to write to disk first.

    var oldFileContents = @"
        Line 1
        Line 2
        Line 3
    ";

    var newFileContents = @"
        Line 1
        Line 2 has changed
    ";

    
    var path = Repository.Init("C:\\tmp");
    var repo = new Repository(path);

    var oldObjectId = repo.ObjectDatabase.Write<Blob>(Encoding.UTF8.GetBytes(oldFileContents));
    var newObjectId = repo.ObjectDatabase.Write<Blob>(Encoding.UTF8.GetBytes(newFileContents));
    var oldBlob = repo.Lookup<Blob>(oldObjectId);
    var newBlob = repo.Lookup<Blob>(newObjectId);
    var diff = repo.Diff.Compare(oldBlob, newBlob);  // Works as expected

    // git repo for in-memory operations
    var in_memory_repo = new Repository();

    // This line failes with the LibGit2SharpException "path cannot exist in repository". As far as I can see this is intentional.
    var in_memory_blob = in_memory_repo.ObjectDatabase.Write<Blob>(Encoding.UTF8.GetBytes(oldFileContents));

Seeing that libgit2sharp already supports working with diffs and patches in-memory, it would be nice to be able to create blobs from strings or streams.

まず、libgit2sharp API における Blob の構築、ObjectDatabase.Write、および Diff.Compare を追跡します。要求されている動作は、文字列またはストリームから blob を作成し、ディスクに書き込んだりディスクベースのリポジトリを必要としたりせずに、それらをインメモリ diff に渡すことです。Issue に示されている古い内容と新しい内容を使ってこれを検証してください。