@ivucica CI on master - .github/workflows: For Bazel RBE, use a BuildBuddy secret as part of CI. Set the BB API header only if the secret is set. The secret will not be set on pull requests, intentionally.

@ivucica CI on master - .github/workflows: For Bazel RBE, use a BuildBuddy secret as part of CI. Set the BB API header only if the secret is set. The secret will not be set on pull requests, intentionally. #72