net: throw ERR_OUT_OF_RANGE if blockList.addSubnet prefix is NaN

Fixes: https://github.com/nodejs/node/issues/36731

PR-URL: https://github.com/nodejs/node/pull/36732


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>