This makes the formatter runners to be git-free if --input_diff_file
is given. They still run `git diff`, if --diff is given. However,
for the purpose of making the presubmit check for format verification
git-free, it's ok as --diff is not used by the presubmit check.
Bug: 386840832
Change-Id: If5ab68fa4e2fec1aafa22e15ddeabb744993342b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6931775
Commit-Queue: Scott Lee <ddoman@chromium.org>
Reviewed-by: Gavin Mak <gavinmak@google.com>
363e910475