internal/pkg: temporary scratch space for cure

This allows for more flexibility during implementation. The use case that required this was for expanding single directory tarballs.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/tar.go

@@ -69,7 +69,7 @@ func (e DisallowedTypeflagError) Error() string {
 }
 
 // Cure cures the [Artifact], producing a directory located at work.
-func (a *tarArtifact) Cure(work *check.Absolute, loadData CacheDataFunc) (err error) {
+func (a *tarArtifact) Cure(work, temp *check.Absolute, loadData CacheDataFunc) (err error) {
 	var tr io.ReadCloser
 
 	{