src: rename Init and Start overloads to something more distinctive

In addition, move the `--help` and `--v8-help` processing out of
`StartNodeWithLoopAndArgs()` and process them earlier - right after
`InitializeNodeWithArgs()`, similar to how they are handled in
the legacy `Init()`.

PR-URL: https://github.com/nodejs/node/pull/26499


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>