Suggestion for CFengine internal log files rotation

Hello,

Regarding bug report https://cfengine.com/dev/issues/3017, here is a try to add rotation for some CFEngine internals log files (promise_summary.log, cfengine/outputs/*), and to also handle rotation for cf3.hostname.runlog file (at the moment it is handled internally with Rotatefiles(), to be consistent.

Any feedback is welcome