Adding impl for tar image overwrite

In order to comply with Test Before Uprev, we add the capability to
overwrite files as provided in a linked tar.

BUG=None
TEST=unit

Cq-Depend: chromium:3182687
Change-Id: Ic287a8639c07d02a54bc12f00e94d3f6a935391a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/3183181
Tested-by: Jaques Clapauch <jaquesc@google.com>
Auto-Submit: Jaques Clapauch <jaquesc@google.com>
Commit-Queue: Jaques Clapauch <jaquesc@google.com>
Reviewed-by: Sean McAllister <smcallis@google.com>
3 files changed