Consider using SafeHandle in Libgit2Object instead of void*

We've had a couple of bug reports against dotnet/runtime with rarely-reproduceable crashes coming from libgit2sharp. We believe that one possible reason could be an interop anti-pattern in Libgit2Object - void*/IntPtr representation of a native handle that can be freed in finalizer. E.g. in this case the finalizer in Libgit2Object may end up calling native free here (and other overloads).

The reason why it's called an anti-pattern can be explained by a short repro in this issue: https://github.com/dotnet/runtime/issues/103522 and a general solution is to use SafeHandle for such handles. Also, see https://learn.microsoft.com/en-us/dotnet/standard/native-interop/best-practices

Reproduction steps

Expected behavior

Actual behavior

Version of LibGit2Sharp (release number or SHA1)

Operating system(s) tested; .NET runtime tested

Commencez dans LibGit2Sharp/Core/Handles/Libgit2Object.cs vers la ligne 88, puis suivez le finalizer et les surcharges de libération native dans LibGit2Sharp/Core/Handles/Objects.cs vers les lignes 502-505. Comparez ces chemins d’ownership avec les recommandations de SafeHandle et les rapports de runtime liés. Le travail est terminé lorsque les chemins pertinents du cycle de vie des handles natifs sont représentés et libérés de manière sûre, sans la race du finalizer signalée.