[WFCORE-250] Use the log file resources and streaming API to download log files

Also removed the `View with CLI` button as it seemed rather difficult to get it to work. The operation is available on each resource.

@ssilvert could you give this a review please? If it's simple enough to add the View with CLI button back and I'm just being stupid let me know. We essentially need to execute `/subsystem=logging/log-file=server.log:read-log-file)`.
Let's just take the MessageHandler out then.  Other than that, I think the code looks good.