[Chainsaw] Minor fixes

I've been doing some messing around with chainsaw the past few days, and I've fixed a few minor issues(and put in some PRs for them) - does somebody(Scott?) want to take a look at them? I can merge stuff if needed, but I'm not sure if somebody else prefers to take some lead on chainsaw. Side

LOG4J2-3075 Formatting timestamps with nanosecond precision

Hello, I am trying to tackle LOG4J2-3075 reporting that JsonTemplateLayout doesn't format nanoseconds. I have done some preliminary study and checked *DatePatternConverter* for inspiration. In a nutshell, this is what *DataPatternConverter*