Logging directly to output log (eg debug logging)

[erikarn]

hi! There isn't a "nice" way to log to the global/world log arbitrary things - eg debugging output.
I open the file a second time for this, but under a decent amount of IO the disk writes get garbled.

It would be nice to either be able to use /log to log to an existing io stream listed in /liststreams, or perhaps have the logfiles available as streams in /liststreams to be written to. They're all tfio streams under the hood, just not registered with the /liststreams subsystem.