Essentially, Workspace (and Screen) types were defined as not
localizable.
In previous code it happended to work by mere chance (code path taken in
`BKE_library_make_local` was conviniently skipping the call to
`BKE_lib_id_make_local` in that case, hence not checking for
`IDTYPE_FLAGS_NO_MAKELOCAL` flag of the localized ID type).
This is a total abuse of this IDType flag, for now removing it.
That specific case (IDtype appendable but nor linkable) requires its own
proper flag, this will be tackled in a later commit.
Issue introduced in rB3be5ce4aad5e.
4a009b54bc