pw_env_setup: Adds CIPD Bazel rules

Adds a set of Bazel rules for fetching the cipd client and downloading
CIPD based dependencies as Bazel remote repositories.

Change-Id: Id15641be7dcac33ddd4bf17f807d8b7f197078ac
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/45140
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Rob Mohr <mohrr@google.com>
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>