Reland "git-cl: Execute clang-format-diff.py using vpython."
Reland "git-cl: Execute clang-format-diff.py using vpython."

This is a reland of 87661afbfc1b59fbfb64183379f2aadaac6c84c7

Set shell=True on Windows, so that vpython.bat can be executed.

Original change's description:
> git-cl: Execute clang-format-diff.py using vpython.
>
> When running git-cl using vpython3, sys.executable is python3.
> Execute clang-format-diff.py using vpython instead, since it has
> not been migrated already.
>
> Bug: 1066187
> Change-Id: I31556acb50ff4256706a313c1393eddad9f903f3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2130926
> Reviewed-by: Josip Sokcevic <4606aec58cba917397ff2e4738f995e4758694f8@google.com>
> Commit-Queue: Edward Lesmes <d05609f027dc667cc37492b1dc1bdea5d60fa82a@chromium.org>

Bug: 1066187
Change-Id: Ia482f13d0f30d625f2f6db3cb4202b7f3f95707b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2135330
Reviewed-by: Josip Sokcevic <4606aec58cba917397ff2e4738f995e4758694f8@google.com>
Commit-Queue: Edward Lesmes <d05609f027dc667cc37492b1dc1bdea5d60fa82a@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools