Auto merge of #83908 - Flying-Toast:master, r=davidtwco

Auto merge of #83908 - Flying-Toast:master, r=davidtwco

Add enum_intrinsics_non_enums lint

There is a clippy lint to prevent calling [`mem::discriminant`](https://doc.rust-lang.org/std/mem/fn.discriminant.html) with a non-enum type. I think the lint is worthy of being included in rustc, given that `discriminant::<T>()` where `T` is a non-enum has an unspecified return value, and there are no valid use cases where you'd actually want this.

I've also made the lint check [variant_count](https://doc.rust-lang.org/core/mem/fn.variant_count.html) (#73662).

closes #83899