Merge #10546

10546: feat: Implement promote_local_to_const assist r=Veykril a=Veykril

Fixes #7692, that is now one can invoke the `extract_variable` assist on something and then follow that up with this assist to turn it into a const.
bors r+

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/hir/src/lib.rs

@@ -1307,6 +1307,10 @@ impl Function {
         db.function_data(self.id).is_unsafe()
     }
 
+    pub fn is_const(self, db: &dyn HirDatabase) -> bool {
+        db.function_data(self.id).is_const()
+    }
+
     pub fn is_async(self, db: &dyn HirDatabase) -> bool {
         db.function_data(self.id).is_async()
     }