[cipd] Make CIPD client platform overridable per installation.
[cipd] Make CIPD client platform overridable per installation.

To switch a depot_tools installation to use mac-arm64 binaries,
run:

  $ cd depot_tools
  $ echo "mac-arm64" > .cipd_client_platform
  $ ./cipd help
  $ <observe "infra/tools/cipd/mac-arm64" in the version string>

Deleting .cipd_client_platform file restores the original logic
(which is currently to use mac-amd64 binaries even on arm64 host).

R=40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org, tandrii@chromium.org
CC=thakis@chromium.org
BUG=1102967

Change-Id: I0248fd913eb3d71f2a228f74a601dc4b12fc8824
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2699692
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools