Move Literal flag detection into recurse phase (#5768)

## Summary

The AST pass is broken up into three phases: pre-visit (which includes
analysis), recurse (visit all members), and post-visit (clean-up). We're
not supposed to edit semantic model flags in the pre-visit phase, but it
looks like we were for literal detection. This didn't matter in
practice, but I'm looking into some AST refactors for which this _does_
cause issues.

No behavior changes expected.

## Test Plan

Good test coverage on these.

crates/ruff_python_stdlib/src/typing.rs

@@ -182,6 +182,11 @@ pub fn is_pep_593_generic_type(call_path: &[&str]) -> bool {
     matches!(call_path, ["typing" | "typing_extensions", "Annotated"])
 }
 
+/// Returns `true` if a call path is `Literal`.
+pub fn is_standard_library_literal(call_path: &[&str]) -> bool {
+    matches!(call_path, ["typing" | "typing_extensions", "Literal"])
+}
+
 /// Returns `true` if a name matches that of a generic from the Python standard library (e.g.
 /// `list` or `Set`).
 ///
@@ -267,6 +272,11 @@ pub fn is_pep_593_generic_member(member: &str) -> bool {
     matches!(member, "Annotated")
 }
 
+/// Returns `true` if a name matches that of the `Literal` generic.
+pub fn is_literal_member(member: &str) -> bool {
+    matches!(member, "Literal")
+}
+
 /// Returns `true` if a call path represents that of an immutable, non-generic type from the Python
 /// standard library (e.g. `int` or `str`).
 pub fn is_immutable_non_generic_type(call_path: &[&str]) -> bool {