[node] add -M support multi-key mode

Signed-off-by: Leo Chen <leo@harmony.one>

scripts/node.sh

@@ -121,6 +121,7 @@ options:
    -V             print out the version of the Harmony binary
    -z             run in staking mode
    -y             run in legacy, foundational-node mode (default)
+   -M             support multi-key mode (default: off)
 
 examples:
 
@@ -157,7 +158,7 @@ BUCKET=pub.harmony.one
 OS=$(uname -s)
 
 unset start_clean loop run_as_root blspass do_not_download download_only metrics network node_type shard_id download_harmony_db db_file_to_dl
-unset upgrade_rel public_rpc staking_mode pub_port
+unset upgrade_rel public_rpc staking_mode pub_port multi_key
 start_clean=false
 loop=true
 run_as_root=true
@@ -170,11 +171,12 @@ shard_id=1
 download_harmony_db=false
 public_rpc=false
 staking_mode=false
+multi_key=false
 ${BLSKEYFILE=}
 
 unset OPTIND OPTARG opt
 OPTIND=1
-while getopts :1chk:sSp:dDmN:tT:i:ba:U:PvVyzn: opt
+while getopts :1chk:sSp:dDmN:tT:i:ba:U:PvVyzn:M opt
 do
    case "${opt}" in
    '?') usage "unrecognized option -${OPTARG}";;
@@ -189,6 +191,7 @@ do
    p) blspass="${OPTARG}";;
    d) download_only=true;;
    D) do_not_download=true;;
+   M) multi_key=true;;
    m) metrics=true;;
    N) network="${OPTARG}";;
    n) pub_port="${OPTARG}";;
@@ -438,6 +441,8 @@ if ${run_as_root}; then
    check_root
 fi
 
+# multi_key mode will use specified keys in .hmy/multikeys directory
+if ! ${multi_key}; then
    case "${BLSKEYFILE}" in
    "")
       unset -v f
@@ -467,6 +472,7 @@ case "${BLSKEYFILE}" in
       msg "using manually specified BLS key file: ${BLSKEYFILE}"
       ;;
    esac
+fi
 
 any_new_binaries() {
    local outdir
@@ -649,10 +655,14 @@ do
       -ip "${PUB_IP}"
       -port "${NODE_PORT}"
       -is_genesis
-      -blskey_file "${BLSKEYFILE}"
       -network_type="${network_type}"
       -dns_zone="${dns_zone}"
    )
+   if ! ${multi_key}; then
+      args+=(
+      -blskey_file "${BLSKEYFILE}"
+      )
+   fi
    if ${public_rpc}; then
       args+=(
       -public_rpc