HDDS-2946. Rename audit log should contain both srcKey and dstKey not just key

[fapifta]

#478 What changes were proposed in this pull request?
In the audit log of a rename request we just log the key to be renamed. The purpose of this PR is to replace key to srcKey and dstKey in the audit log message in case of a rename.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-2946

How was this patch tested?

I haven't find any particular junit test that tests actual audit log messages, and I haven't added one, though I have this patch applied on a cluster, and used the new type of audit log to trace down multiple renames properly. I am happy to discuss how to add a junit test if there is any place for it, and if there is any reason to test the particular queries audit contents, I don't see it necessary as the general facilities we are using for audit log message creation are already tested.

[adoroszlai]

Thanks @fapifta for the contribution.

For unit test, I think a good place to add an assertion about audit map contents would be in TestOMKeyRenameRequest. It uses a mock AuditLogger (inherited from TestOMKeyRequest).

[elek]

+1 thanks the improvement @fapifta and the review @adoroszlai

As it's a small change I will commit it with the existing test, if you open a new Jira to improve the test coverage of this area (as suggested by @adoroszlai ) I promise a quick review ;-)