pw_env_setup: add gitiles command line client
pw_env_setup: add gitiles command line client

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Change-Id: I58659cdd49ef197f02b746f5504207a4fe8bef1c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/13791
Reviewed-by: Keir Mierle <69344103cc60b36d6e1fbdc31ce6504b2286c646@google.com>
Commit-Queue: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed