Better detection for old MS Office files

Better detection for old MS Office files

* Introduce MSCompoundFileReader, which reads the CFB directory and
  detects the file type from well-known names in the root directory
* Do not detect a ZIP file if the EOCDR is not at the end. Other
  containers, especially CFB files, may contain ZIP files embedded
  within them in the last 64KB, but this is not a security concern
  unless the EOCDR is exactly at the end of the file.

Bug: T40432
Change-Id: Id5b1a258ccf3c3c8951e32f6b7a5b1bafe941082