chore: set up if

[jonybur]

Description

Problem*

Resolves #2993

Summary*

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[TomAFrench]

I'm inclined to omit this until we have proper line breaking support, I think it would be sad to lose the ability to do let min = if a < b { a } else { b };

[jonybur]

Omitting until we have proper line breaking support