libbrillo: Add GetDaemonPathForTemporaryUserHome to cryptohome utilities

Similar to GetDaemonPath, GetDaemonPathForTemporaryUserHome returns
the directory where the passed daemon should store its data for a
temporary user home mount.

BUG=chromium:722371
TEST=Tests still pass, actual functionality tested by CL
https://chromium-review.googlesource.com/c/562158/

Change-Id: I06efeed13bc611bab9baa542de47d9f7112e792e
Reviewed-on: https://chromium-review.googlesource.com/562277
Commit-Ready: Pavol Marko <pmarko@chromium.org>
Tested-by: Pavol Marko <pmarko@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
2 files changed