chore: add a smoke test usage of s3_sync

[alexeagle]

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Changes are visible to end-users: no

Test plan

• Manual testing; please provide instructions so we can reproduce:

Check that the rules work on MacOS:

% bazel run :upload_dry_run
INFO: Analyzed target //:upload_dry_run (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //:upload_dry_run up-to-date:
  bazel-bin/upload_dry_run/s3_sync.sh
INFO: Elapsed time: 0.104s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Running command line: bazel-bin/upload_dry_run/s3_sync.sh
Copying the following artifacts to s3://my-test-bucket/release_destination:
BUILD

Copying BUILD to s3://my-test-bucket/release_destination/BUILD
upload failed: ./BUILD to s3://my-test-bucket/release_destination/BUILD An error occurred (InvalidAccessKeyId) when calling the PutObject operation: The AWS Access Key Id you provided does not exist in our records.