Color mode detection on FreeBSD

[Swat-SomeBug]

Description Allow correct detection of colour mode on FreeBSD when redirecting to file. Don't print out colour codes when this is done by default.

Additional context ANSIColourImpl::useImplementationForStream checks if the stream is being directed and if true sets useColour to false. Here CATCH_INTERNAL_HAS_ISATTY is defined only when CATCH_PLATFORM_LINUX or CATCH_PLATFORM_MAC is true. Is it possible to allow something like CATCH_PLATFORM_FREEBSD as well?