build_api: add remote_test_driver.proto

This creates the build API endpoint for running
src/scripts/create_remote_test_driver,
which puts together the files needed to `docker build` the remote test
driver image.

BUG=chromium:1151028
TEST=regen

Change-Id: I6a7b1ac84ed1589e834601c0e402253622c371e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2595923
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Alex Klein <saklein@chromium.org>
Auto-Submit: Sean Abraham <seanabraham@chromium.org>
2 files changed