Deprecate `*.Safe` modules

I noticed that there are a bunch of *.Safe modules, but they seem to export exactly the same stuff as their * counterparts (except for Data.Array.MArray which additionally exports the new modifyArray and modifyArray' functions). Looking at a6b42f2b, there originally were unsafe functions in Data.Array.{IO, MArray, ST, Storable} that were deprecated and moved to Data.Array.Unsafe (and then removed from the original modules in 6b7dc954). So I think the *.Safe modules can be deprecated now, since there is no difference with the * variants and it just confuses people why there are two modules exporting the same stuff (like me).