[roll third_party/pigweed] pw_transfer: Support reads in Python test client

This commit updates the Python client used in the pw_transfer
integration test to support the new "read" action, which reads data
from the server and writes it to a file specified via the config.

The harness does not yet make use of this functionality. The integration
test continues to pass.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/94901

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 9e7dc9ccff18724..4a217c7500f074b
Roller-URL: https://ci.chromium.org/b/8813617318708807217
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8813617318708807217
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I306d69d28c985839b6fe6f43846f619e7cdc9f7f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/95441
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
1 file changed