Generate core message request and responses for
golden data tests.
This CL does not have any golden data. The golden data
will be added to a google3 CL.
To turn on dumping of golden data, set the environment
variable DUMP_GOLDEN_DATA to "yes".
Merged from https://widevine-internal-review.googlesource.com/171750
Change-Id: I7ae2d76ec7330d9131aae98dfd07b7909d10f726
