Rollup merge of rust-lang#134277 - notriddle:notriddle/inline-into, r=GuillaumeGomez

rustdoc-search: handle `impl Into<X>` better

This PR fixes two bugs I ran into while searching the compiler docs:

- It omitted an `impl Trait` entry in the type signature field, producing `TyCtxt, , Symbol -> bool`
- It didn't let me search for `TyCtxt, DefId, Symbol -> bool` even though that's a perfectly good description of the function I was looking for (the function actually used `impl Into<DefId>`

r? ``@GuillaumeGomez`` cc ``@lolbinarycat``

Author: matthiaskrgr

core/src/convert/mod.rs

@@ -443,6 +443,7 @@ pub trait AsMut<T: ?Sized> {
 /// [`Vec`]: ../../std/vec/struct.Vec.html
 #[rustc_diagnostic_item = "Into"]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[doc(search_unbox)]
 pub trait Into<T>: Sized {
     /// Converts this type into the (usually inferred) input type.
     #[must_use]
@@ -577,6 +578,7 @@ pub trait Into<T>: Sized {
     all(_Self = "&str", T = "alloc::string::String"),
     note = "to coerce a `{T}` into a `{Self}`, use `&*` as a prefix",
 ))]
+#[doc(search_unbox)]
 pub trait From<T>: Sized {
     /// Converts to this type from the input type.
     #[rustc_diagnostic_item = "from_fn"]