Retain hierarchical structure in file system mirror (#5844) The `FileSystemSnapshotter` now returns a root for each snapshotted file, possible containing all the children in hierarchy as the directory would no the file system.
This PR also contains some performance related changes: - Stop interning path segments: That was only necessary when we stored the same path segments in many RelativePath objects. We don't do this any more, so interning should not be necessary and make things faster. Actually, up-to-date assemble on largeMonolithicJavaProject (parallel false) is about 40ms faster with this change (2.5 %).
- Don't use IndexedNormalizedFileSnapshots: It seems like there are no real performance gains by using IndexedNormalizedFileSnapshots.