Create `verify_vrb` utils function

[Hanne Oberman]

    vrb <- substitute(vrb)
    if (vrb[1] == "all") {
      vrb <- names(data)
    } else {
      vrb <- names(dplyr::select(as.data.frame(data), {{vrb}}))
    }

[Hanne Oberman]

Maybe not verify but extract or process, or vrb_to_cols?