Add test for issue 53096

Author: jackh726

src/test/ui/issues/issue-53096.rs

@@ -0,0 +1,9 @@
+// check-pass
+#![feature(const_fn)]
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Fn() -> usize;
+const fn bar() -> Foo { || 0usize }
+const BAZR: Foo = bar();
+
+fn main() {}