MinidumpFileWriter writes the top-level object to a minidump file. This
consists of a MINIDUMP_HEADER and a list of MINIDUMP_DIRECTORY entries
that point to streams, which are second-level objects in minidump files.
This change also adds the base class for stream writers,
MinidumpStreamWriter.
TEST=minidump_test MinidumpFileWriter*
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/432863006
