fix: ref match uses unified type

Example
---
```rust
struct S<T>(T);
fn foo<T>(s: &mut S<T>) {}
fn main() {
    let mut ssss = S(2u32);
    foo($0);
}
```

**Before this PR**

```text
st S(…) S(T) []
st &mut S(…) [type]
lc ssss S<u32> [local]
```

**After this PR**

```text
st S(…) S(T) []
st &mut S(…) [type]
lc ssss S<u32> [local]
lc &mut ssss [type+local]
```

Author: A4-Tacks

crates/ide-completion/src/render.rs

@@ -713,7 +713,9 @@ fn compute_ref_match(
     if let Some(expected_without_ref) = &expected_without_ref
         && (completion_without_ref.is_none()
             || completion_ty.could_unify_with(ctx.db, expected_without_ref))
-        && completion_ty.autoderef(ctx.db).any(|ty| ty == *expected_without_ref)
+        && completion_ty
+            .autoderef(ctx.db)
+            .any(|ty| ty.could_unify_with(ctx.db, expected_without_ref))
     {
         cov_mark::hit!(suggest_ref);
         let mutability = if expected_type.is_mutable_reference() {
@@ -2917,6 +2919,26 @@ fn main() {
                 fn main() fn() []
             "#]],
         );
+        check_relevance(
+            r#"
+struct S<T>(T);
+fn foo<T>(s: &mut S<T>) {}
+fn main() {
+    let mut ssss = S(2u32);
+    foo($0);
+}
+            "#,
+            expect![[r#"
+                st S(…) S(T) []
+                st &mut S(…) [type]
+                lc ssss S<u32> [local]
+                lc &mut ssss [type+local]
+                st S S<{unknown}> []
+                st &mut S [type]
+                fn foo(…) fn(&mut S<T>) []
+                fn main() fn() []
+            "#]],
+        );
     }
 
     #[test]