[roll pigweed] pw_transfer: Report errors when a transfer can't be started

Following the transfer thread event-based refactor, pw_transfer would
fail silently when attempting to start a new transfer without any
available contexts. This updates the transfer thread to report these
errors both client- and server-side.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/104740

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 84d93d0d93a23a3..9af45f52bf64252
Roller-URL: https://ci.chromium.org/b/8806829722176402065
Cq-Cl-Tag: roller-builder:pigweed-zephyr-roller
Cq-Cl-Tag: roller-bid:8806829722176402065
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I8ae3390b76ca5a1a3c655fece8e7bb1c699a612f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/104843
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
tree: 2e52c95dd437fda51298f8be9adea0689fb814b5
  1. .gitmodules
  2. test.sh