Block subdirs of Android for SAF and normalize the path

- When the Apps launch SAF, they can set initial uri to launch the
  specific directory. Block the access for data/obb/sandbox
  directories of Android
- Normalize path (E.g. the path includes . or ..) to avoid
  unexpected behavior

Bug: 200034476
Bug: 220066255
Test: atest ExternalStorageProviderTest
Test: atest DocumentsTest
Change-Id: I226a9c25710fcf78d14d775eb3270bfd3b491dd3