Add prepare_to_publish_to_s3_params (#23)

* Add prepare_to_publish_to_s3_params

* Fix shellcheck concerns

Author: jkmassel

bin/prepare_to_publish_to_s3_params

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+PARAMS=(--sha1="$BUILDKITE_COMMIT")
+[[ -n "$BUILDKITE_TAG" ]] && PARAMS+=(--tag-name="$BUILDKITE_TAG")
+[[ -n "$BUILDKITE_BRANCH" ]] && PARAMS+=(--branch-name="$BUILDKITE_BRANCH")
+[[ -n "$BUILDKITE_PULL_REQUEST" && "$BUILDKITE_PULL_REQUEST" != "false" ]] && PARAMS+=(--pull-request-number="$BUILDKITE_PULL_REQUEST")
+echo "${PARAMS[@]}"