[red-knot] Enhancing Diagnostics for Compare Expression Inference (#13819)

## Summary

- Refactored comparison type inference functions in `infer.rs`: Changed
the return type from `Option` to `Result` to lay the groundwork for
providing more detailed diagnostics.
- Updated diagnostic messages.

This is a small step toward improving diagnostics in the future.

Please refer to #13787

## Test Plan

mdtest included!

---------

Co-authored-by: Carl Meyer <carl@astral.sh>

crates/red_knot_python_semantic/resources/mdtest/comparison/unsupported.md

@@ -7,11 +7,21 @@ reveal_type(a)  # revealed: bool
 b = 0 not in 10  # error: "Operator `not in` is not supported for types `Literal[0]` and `Literal[10]`"
 reveal_type(b)  # revealed: bool
 
-c = object() < 5  # error: "Operator `<` is not supported for types `object` and `Literal[5]`"
+c = object() < 5  # error: "Operator `<` is not supported for types `object` and `int`"
 reveal_type(c)  # revealed: Unknown
 
 # TODO should error, need to check if __lt__ signature is valid for right operand
 d = 5 < object()
 # TODO: should be `Unknown`
 reveal_type(d)  # revealed: bool
+
+int_literal_or_str_literal = 1 if flag else "foo"
+# error: "Operator `in` is not supported for types `Literal[42]` and `Literal[1]`, in comparing `Literal[42]` with `Literal[1] | Literal["foo"]`"
+e = 42 in int_literal_or_str_literal
+reveal_type(e)  # revealed: bool
+
+# TODO: should error, need to check if __lt__ signature is valid for right operand
+# error may be "Operator `<` is not supported for types `int` and `str`, in comparing `tuple[Literal[1], Literal[2]]` with `tuple[Literal[1], Literal["hello"]]`
+f = (1, 2) < (1, "hello")
+reveal_type(f)  # revealed: @Todo
 ```