[red-knot] Infer subscript expression types for bytes literals (#13901)

## Summary

Infer subscript expression types for bytes literals:
```py
b = b"\x00abc\xff"

reveal_type(b[0])  # revealed: Literal[b"\x00"]
reveal_type(b[1])  # revealed: Literal[b"a"]
reveal_type(b[-1])  # revealed: Literal[b"\xff"]
reveal_type(b[-2])  # revealed: Literal[b"c"]

reveal_type(b[False])  # revealed: Literal[b"\x00"]
reveal_type(b[True])  # revealed: Literal[b"a"]
```


part of #13689
(https://github.com/astral-sh/ruff/issues/13689#issuecomment-2404285064)

## Test Plan

- New Markdown-based tests (see `mdtest/subscript/bytes.md`)
- Added missing test for `string_literal[bool_literal]`

crates/red_knot_python_semantic/src/lib.rs

@@ -21,5 +21,6 @@ mod semantic_model;
 pub(crate) mod site_packages;
 mod stdlib;
 pub mod types;
+mod util;
 
 type FxOrderSet<V> = ordermap::set::OrderSet<V, BuildHasherDefault<FxHasher>>;