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

Commencez par GitDiffMargin/Git/GitCommands.cs à la ligne 43 et par l’issue GitDiffMargin associée, puis examinez la manière dont Git et libgit2sharp représentent les dépôts sparse-checkout. Reproduisez l’exception de version du dépôt avec un dépôt sparse-checkout et vérifiez que l’ouverture d’un tel dépôt n’échoue plus.