Add "delete" commands

[funnell]

Having a set of "delete" commands for removing experiments, samples, etc. with associated analyses and raw data and results files would be convenient.

It would make sense to have some protection against mistakes. Something like showing a full list of everything that would be changed, and someone would need to append "--commit" to the command for the changes to occur.

It might also make sense to do something similar to what GitHub does for deleting repositories, like making the user type in the e.g. experiment's id before a delete would be committed.

And I suppose the deleted raw files could be moved to a "trash" folder, similar to how analyses can get moved to .analyses_trash