afdo_tools: add update_kernel_afdo.py

The intent is to replace `update_kernel_afdo` with this.

BUG=b:329449239
TEST=Ran the script. Example CL this generated for canary:
TEST=crrev.com/c/5372145

Change-Id: If5ca0f9055a60b0e7dedacd1c8b76aadc55561f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/5373229
Commit-Queue: George Burgess <gbiv@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
3 files changed