process: add lineLength to source-map-cache

Without the line lengths of in-memory transpiled source, it's not
possible to convert from byte ofsets to line/column offsets.

PR-URL: https://github.com/nodejs/node/pull/29863


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>