Add a way to disable exporting conditionally

[bitspittle]

Perhaps an option to the @Page() annotation? Or maybe an annotation on its own so you can configure rules that match against a large area, like "don't export anything under the 'pages.admin'" package or something

[bitspittle]

~~Also, kobweb export should take an option for disabling the part of exporting that requires Chrome. Some users don't need page snapshots but they still need to export (so files are copied to the right place). One user told me they don't have chrome installed on their machine and don't want to install it.~~

(This comment isn't relevant anymore as we now use Playwright to manage browser installation)

[bitspittle]

Now supported in 0.15.3