afdo_tools: Improve update_kernel_afdo script

By default the script now will create a commit and give a prompt
on how to submit the change.
Neither sync or clean-up needed to submit the change.
The new workflow doesn't touch existing checkout and ignores (and keeps)
any local changes.
Without arguments the script tries to update metadata in
all channels: canary (main), beta and stable.
To update afdo metadata in specific channel run:
./update_kernel_afdo canary|beta|stable.

BUG=None
TEST=afdo_tools/update_kernel_afdo produces 3 commits in release-R92,
  release-R91 and release-R90

Change-Id: I61c8c743a4634d2ab4e4837f8a31a31a6cea2c2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2872860
Tested-by: Denis Nikitin <denik@chromium.org>
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: George Burgess <gbiv@chromium.org>
Commit-Queue: Denis Nikitin <denik@chromium.org>
1 file changed