Allow future posts, maybe just for some collections?

[NickleDave]

Currently when we add posts to _events, we need to leave out a date from the title to get them to render immediately. See comment from @lparsons here:
#911 (review)

One issue is that if you use a full date for the events (with the day), Jekyl decides that this is a blog post that isn't ready to be published yet and won't render the page (thus the artifact is missing in CircleCI). Try renaming the file to _events/2022/2022-09-dei-media-club.md.

A way to avoid this would be to set future: true in _config.yml as suggested by @exoticDFT
#911 (comment)

Do we actually care to post things that will only become available after a date? You can add an option to allow future posts. On another website I have, I just have an option at the root level of the _config.yml. I think you may be able to add it to the collection level instead. The option is below.
future: true

Not sure if there's a case where we want to hide any posts we are merging in at the moment?
But if so we might be able to add it a the collection level, as @exoticDFT suggests