Hide in stream context option

[buddh4]

Is your feature request related to a problem? Please describe.

There should be a way of hiding individual content as files etc from the stream. Perhaps by adding a "Hide in stream" feature. This feature should only be available for some content types, since it makes no sense to hide for example a post, which is not available anywhere else.

[marc-farre]

+1, this feature is asked regularly. Could be done in conjunction with https://github.com/humhub/humhub/issues/3714