Support git repositories which use the sparse checkout git feature

Hello!
Git introduced a new feature called sparse-checkout This command is very useful in large repositories containing a lot of projects. Using sparse-checkout and partial repository clone allow substantially reduce occupied by the repository space on local disk.

GitDiffMargin is a useful extension for Visual Studio, This extension uses the libgit2sharp. The extension is not work with repositories uses sparse-checkout because such repositories are not supported.

Reproduction steps

Git Diff Margin get an exception unsupported repository version 1. Only versions up to 0 are supported. while creating a Repository on this line.

Refer to the according GitDiffMargin issue for more info:https://github.com/laurentkempe/GitDiffMargin/issues/356

Beginnen Sie mit GitDiffMargin/Git/GitCommands.cs in Zeile 43 und dem verknüpften GitDiffMargin-Issue. Überprüfen Sie anschließend, wie sparse-checkout-Repositories von Git und libgit2sharp dargestellt werden. Reproduzieren Sie die Repository-Versionsausnahme mit einem sparse-checkout-Repository und verifizieren Sie, dass das Öffnen eines solchen Repositorys nicht mehr fehlschlägt.