test: add tests for validateNumber/validateString

PR-URL: https://github.com/nodejs/node/pull/34672


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Pranshu Srivastava <rexagod@gmail.com>
Reviewed-By: Ricky Zhou <0x19951125@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>