message: [docker] Improvements to mint run script
  Better argument extraction, publish port so it can be tested.
diff: set -ex
  -IMAGE="$1"
  +IMAGE="${1?[Specify docker image]}"
  +AC_HOST="${2?[Specify validator AC hostname/address]}"
  +AC_PORT="${3?[Specify validator AC port]}"
  +LOG_LEVEL="${4:-info}"
  CONFIGDIR="$(dirname "$0")/../../terraform/validator-sets/dev"
  docker network create --subnet 172.18.0.0/24 testnet || true
  -docker run -p 8000:8000 -e AC_HOST=$2 -e AC_PORT=$3 -e LOG_LEVEL=$4 \
  +docker run -p 8000:8000 -e AC_HOST="$AC_HOST" -e AC_PORT="$AC_PORT" -e LOG_LEVEL="$LOG_LEVEL" \
  -e TRUSTED_PEERS="$(cat $CONFIGDIR/trusted_peers.config.toml)" \
  -e MINT_KEY="$(base64 $CONFIGDIR/mint.key)" \
  - --network testnet $IMAGE
  + --network testnet --publish 8080:8000 "$IMAGE"
  