fix to_meta_type to fix the member/method resoution panic

Author: oconnor663

crates/ty_python_semantic/resources/mdtest/annotations/new_types.md

@@ -53,6 +53,10 @@ g(Bar(Foo(42)))
 h(42)  # error: [invalid-argument-type] "Argument to function `h` is incorrect: Expected `Bar`, found `Literal[42]`"
 h(Foo(42))  # error: [invalid-argument-type] "Argument to function `h` is incorrect: Expected `Bar`, found `Foo`"
 h(Bar(Foo(42)))
+
+# Method lookup works.
+def _(x: Bar):
+    reveal_type(x.bit_length())  # revealed: int
 ```
 
 ## The name must be a string literal

crates/ty_python_semantic/src/types.rs

@@ -6748,9 +6748,7 @@ impl<'db> Type<'db> {
             // understand a more specific meta type in order to correctly handle `__getitem__`.
             Type::TypedDict(typed_dict) => SubclassOfType::from(db, typed_dict.defining_class()),
             Type::TypeAlias(alias) => alias.value_type(db).to_meta_type(db),
-            Type::NewTypeInstance(newtype) => {
-                Type::KnownInstance(KnownInstanceType::NewType(newtype))
-            }
+            Type::NewTypeInstance(newtype) => Type::from(newtype.base_class_type(db)),
         }
     }