lib: extract validateNumber validator

Pulls out another common argument validator to `internal/validators`

PR-URL: https://github.com/nodejs/node/pull/22249


Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>