move fsmonitor out into a Nimble package

[firminochangani]

The fsmonitor page is returning the 404 error. The error page shows the default message from nginx and its version. I would suggest a custom 404 page.

https://nim-lang.org/docs/fsmonitor.html

[dom96]

We need to move this module out into a nimble package.

[dom96]

Actually, here is an issue with some discussion so I'm going to close this in favour of it: #6718