tar: find package root dir in pipeToFileSystem

While iterating over all files in tarball set root_dir in diagnostic if
there is single root in tarball. Will be used in package manager with
strip_components = 0 to find the root of the fetched package.
b1e70edd90Igor Anić committed on 4/3/2024, 5:44:51 PMparent24304a4
1 file changedLine totals unavailable