tools: enable Node.js command line flags in node_mksnapshot

Pass the flags down to node_mksnapshot so that we can use them
when generating the snapshot (e.g. to debug or enable V8 flags)

PR-URL: https://github.com/nodejs/node/pull/32984


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>