Summary

This fixes #15745

Also, I haven't found a trait/helper to get expression precedence. Even though at least 3 rules check precedence when generating fixes. Generally speaking, unless/until fixes are done via AST generation - many (all?) fixes involving expression rewrites would need to consult precedence to handle parens. Unless I am mistaken.

Thus, I've implemented an enum and a trait. But I didn't dare doing that in semantic/AST crates, although I believe it would be helpful to move them there.

@AlexWaygood @dylwil3 you'll know the codebase better, let me know if you think it should be elevated to some core base crate. If you do, I am happy to implement this, but will need your guidance on where you'd like it to reside.

Test Plan

• Updated test case with 2 examples from the issue + a couple of mine, including one that would generate invalid python program before this fix
• cargo nextest run (check updated snapshot)