support jmx port for seata-server.sh

[funky-eyes]

Why you need it?

Is your feature request related to a problem? Please describe in details
方便jvm相关的exporter或jconsole采集线程数，gc次数等metric数据，应该开放jmx port的设置

JMX_PORT=$JMX_PORT
JMX_OPTS=$JMX_OPTS
if [ -z "$JMX_OPTS" ]; then
  JMX_OPTS=" -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.authenticate=false  -Dcom.sun.management.jmxremote.ssl=false "
fi

if [ -z "$JMX_PORT" ]; then
  JMX_OPTS=" $JMX_OPTS -Dcom.sun.management.jmxremote.port=${JMX_PORT:="10055"} -Dcom.sun.management.jmxremote.rmi.port=${JMX_PORT:="10055"} "
fi

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