[rust] missing flow typegen config options

[kassens]

The Rust compiler doesn't have all the options and capabilities to print Flow code that we have in the OSS compiler (we cut some corners in configurability to get this massive project over the finish line!)

Let's track here what options are missing and if someone is working on a PR for parts of it!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[alunyov]

I think we're now have all of the typegen flag supported in rust (with this commit: dc74f42)