Display Union of Literals as a Literal

[Glyphack]

Summary

Resolves #14988

Display union of Literals like other type checkers do.

With this change we lose the sorting behavior. And we show the types as they appeared. So it's deterministic and tests should not be flaky.
This is similar to how Mypy reveals the type.

In some cases this makes it harder to know what is the order in revealed type when writing tests but since it's consistent after the test fails we know the order.

Test Plan

I adjusted mdtests for this change. Basically merged the int and string types of the unions.

In cases where we have types other than numbers and strings like this one. We only group the strings and numbers as the issue suggsted.

def _(flag: bool, flag2: bool):
    if flag:
        f = 1
    elif flag2:
        f = "foo"
    else:
        def f() -> int:
            return 1
    # error: "Object of type `Literal[1, "foo", f]` is not callable (due to union elements Literal[1], Literal["foo"])"
    # revealed: Unknown | int
    reveal_type(f())

pyright example

mypy example

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[carljm]

This looks good to me! Will delete the contentious comment and then merge :) Thank you !!