When jwt.filer_signing.key is set, the filer's IamGrpcServer requires
a Bearer token on every IAM RPC. The shell's s3.* IAM commands dialed
without that header and failed with Unauthenticated. Route them through
a small helper that mints a token from the same key viper-loaded from
security.toml and appends it as outgoing metadata, matching the credential
grpc_store pattern.
Chris LuandGitHub
37e6263efe