Prevent users from copying full fixed datasets and explain how to use them directly

[prioux]

This weekend a user couldn't figure out how to select a bunch of files from an installed dataset directly and instead proceeded to copy them all into their own private project.

This duplicated over 100GB of files.

The user wanted to select these data files alongside their own license file for a tool (that one in their own project) in order to launch that tool.

We need a better way to explain to users how to select files that are in different projects.

Also, we might want to prevent copying of files from fixed datasets. There is already a clumsy mechanism that limits what can be copied where (a DP can be set so that its files cannot be copied to other specific DPs) but this ties to some of the issues already in GitHub ( #1004 )

Also, the user attempted to upload their license file to the dataset DP (this was allowed because of #1399 )

[MontrealSergiy]

Is it @xmpham's task to add a guide on using several projects in the same time to the wiki, or should an admin update the project description, or perhaps it belongs on the project page?

By the way, IMHO, the "Special 'All' Projects" tab is written in a way that may confuse and scare non-programmers. I suggest changing it to something more user-friendly, like "Show all the files" or "Files from all projects," which could be clearer for regular, non-privileged users.

[MontrealSergiy]

@prioux is fixed dataset stands for selected datasets?

I an alternative suggestion, if a dataset is large ( over 2G?) give him a warning, that for most use cases he can use it directly, and also link to guide on how to combine files from different datasets.