zip_archive: validate data descriptor contents.

- Ensure that the compressed and uncompressed lengths in the data
  descriptor match those in the central directory.

- Calculate CRCs for compressed entries and ensure that those CRCs
  match the information in the central directory / data descriptor.
  This is currently guarded by a flag and will be turned on at a
  later stage.

- Finally, always trust the LFH when it comes to indicating the
  existence of a data descriptor. We no longer require this info to
  match the central directory to bring this in line with other zip
  processing tools. (see NOTE in the included change).

Bug: 62047801
Test: zip_archive_test
Change-Id: Icceea66a8b1937c08a4af9aee97bc77ad7218c0f