tools: fix config serialization w/ long strings

So that “config.gypi” gets serialized correctly in cases such as:

    ./configure --v8-options='--write-protect-code-memory \
    --wasm-write-protect-code-memory'

Where “v8_options” gets prettyprinted into a multiline string.

PR-URL: https://github.com/nodejs/node/pull/35982


Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>