meta: alphabetize .mailmap file

The file is mostly sorted in lexical order but there are exceptins, a
few of them significant. This puts everything in lexical order.

PR-URL: https://github.com/nodejs/node/pull/39434


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>