GitRemoteCallbacks: add url_resolve callback

Author: ethomson

LibGit2Sharp/Core/GitRemoteCallbacks.cs

@@ -34,5 +34,7 @@ internal struct GitRemoteCallbacks
         internal IntPtr transport;
 
         internal IntPtr payload;
+
+        internal NativeMethods.url_resolve_callback resolve_url;
     }
 }

LibGit2Sharp/Core/NativeMethods.cs

@@ -2037,6 +2037,13 @@ internal static extern unsafe int git_cherrypick_commit(out git_index* index,
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
         internal static extern void git_transaction_free(IntPtr txn);
 
+        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+        internal delegate int url_resolve_callback(
+            IntPtr url_resolved,
+            IntPtr url,
+            int direction,
+            IntPtr payload);
+
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
         internal static extern unsafe void git_worktree_free(git_worktree* worktree);