Improve the verbosity of `dl_read_gcp`

[biodavidjm]

• Change default to verbose = TRUE
• It should let the user know when the file is not available, and the possible reasons, e.g., he file does not exist in GCP

This could be added here

  if(file.exists(new_path)){
    dt <- data.table::fread(new_path, sep=sep, header=header,...)
    return(dt)
  }else{
    stop("- Problems loading the file")
  }