Auto merge of #16707 - regexident:pub-sema-impl, r=Veykril

Export `SemanticsImpl` from `ra_ap_hir` crate, since it's already exposed via `Semantics.deref()`

The `SemanticsImpl` type is already de-facto exposed via `<Semantics as Deref>::Target`.

By not being part of the public crate interface it however doesn't get included in the documentation, resulting in a massive blind spot when it comes to `ra_ap_hir`'s type resolution APIs.

crates/hir/src/lib.rs

@@ -93,7 +93,8 @@ pub use crate::{
     diagnostics::*,
     has_source::HasSource,
     semantics::{
-        DescendPreference, PathResolution, Semantics, SemanticsScope, TypeInfo, VisibleTraits,
+        DescendPreference, PathResolution, Semantics, SemanticsImpl, SemanticsScope, TypeInfo,
+        VisibleTraits,
     },
 };