Add a --preserve-symlinks-main option

[dgoldstein0]

which behaves like --preserve-symlinks but for require.main. Fixes #19383

Checklist

I realize there is more to do here, but I wanted to send this out early for feedback. If there aren't any qualms with the approach, I'll figure out testing / documentation / etc.

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines