account_tool: Add script to install accounts to sysroot

BUG=brillo:1112
TEST=Hand testing
CQ-DEPEND=CL:275684

Change-Id: I24c556a43510ef1b007b7f4db42eb27f25fc1596
Reviewed-on: https://chromium-review.googlesource.com/275353
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
2 files changed