Rollup merge of #143219 - zachs18:patch-5, r=tgross35

Show auto trait and blanket impls for `!`

Add an empty `impl ! {}` so rustdoc shows auto trait impls and blanket impls on `!`'s documentation page.

This is already done for [unit](https://github.com/zachs18/rust/blob/2f0ad2a71e4a4528bb80bcb24bf8fa4e50cb87c2/library/core/src/primitive_docs.rs#L493), [tuples](https://github.com/zachs18/rust/blob/2f0ad2a71e4a4528bb80bcb24bf8fa4e50cb87c2/library/core/src/primitive_docs.rs#L1148), and [`fn` pointers](https://github.com/zachs18/rust/blob/2f0ad2a71e4a4528bb80bcb24bf8fa4e50cb87c2/library/core/src/primitive_docs.rs#L1874).

cc #97842 ``@notriddle`` which added the same for unit and tuple.

<details><summary>Comparison</summary>

[Before (current):](https://doc.rust-lang.org/nightly/std/primitive.never.html)
![image](https://github.com/user-attachments/assets/eab8126d-8d65-46d4-8dc7-3680f3162ce3)

After:
![image](https://github.com/user-attachments/assets/e0868113-ebef-4c64-ac30-dfe740d7ea38)
</details>

``@rustbot`` label A-docs F-never_type

Author: dianqk

library/core/src/primitive_docs.rs

@@ -316,6 +316,11 @@ mod prim_bool {}
 #[unstable(feature = "never_type", issue = "35121")]
 mod prim_never {}
 
+// Required to make auto trait impls render.
+// See src/librustdoc/passes/collect_trait_impls.rs:collect_trait_impls
+#[doc(hidden)]
+impl ! {}
+
 #[rustc_doc_primitive = "char"]
 #[allow(rustdoc::invalid_rust_codeblocks)]
 /// A character type.