GT's html export machinery does not have an obvious hookpoint to remove UUIDs from output file names

[botwhytho]

LeHtmlBookExportCommandLineHandler>>#defaultHypertextReferenceBuilder exists and there are two classes, one that creates links between pages with .html extension and one without.

Looking at how page names get written in the output led me to LeExportPageLinksBuilder>>#buildPageLink:. Unfortunately didn't see any 'easier' option than to attach an 'instead' Metalink on that method, a rather brittle solution. Otherwise I would have to clone a bunch of classes and that defeats the purpose of being able to reuse LeHtmlBookExportCommandLineHandler, which does have some convenient customization points (and command line overrides) for other things. See the changes I had to make to the method below. Seems like the TLeExportHypertextReferenceBuilder Trait should have a bit more functionality so something like removing UUIDs from page names is possible in a custom class that uses that trait.