add import/export command and test #6972

[carlvine500]

Which Issue(s) This PR Fixes

Fixes #6971 refer failed pull request #6972

Brief Description

1. migrate message across env: we switch our system from aws to aliyun , some message still not consumed in aws , we should migrate message from aws to aliyun ==> just use exportMessage and importMessage .
2. fix some wrong message: after deploy some bug , the message format is not correct ==> we can exportMessage with json body --> modify message body --> importMessasge
3. trace bug in lots of message body ==> after export message with json/text format ,we could easily search some keywords to view message detail , such as grep keyword messageFile

How Did You Test This Change?

1. exportMessage: mock broker , fetch some messages and export to file , at the same time , show result 100% on system.out
2. importMessage: mock broker , read a message file and send message to broker , at the same time , show result 100% on system.out

example usage