[ty] Detect illegal multiple inheritance with NamedTuple (#19943)

ty.schema.json

@@ -561,6 +561,16 @@
             }
           ]
         },
+        "invalid-named-tuple": {
+          "title": "detects invalid `NamedTuple` class definitions",
+          "description": "## What it does\nChecks for invalidly defined `NamedTuple` classes.\n\n## Why is this bad?\nAn invalidly defined `NamedTuple` class may lead to the type checker\ndrawing incorrect conclusions. It may also lead to `TypeError`s at runtime.\n\n## Examples\nA class definition cannot combine `NamedTuple` with other base classes\nin multiple inheritance; doing so raises a `TypeError` at runtime. The sole\nexception to this rule is `Generic[]`, which can be used alongside `NamedTuple`\nin a class's bases list.\n\n```pycon\n>>> from typing import NamedTuple\n>>> class Foo(NamedTuple, object): ...\nTypeError: can only inherit from a NamedTuple type and Generic\n```",
+          "default": "error",
+          "oneOf": [
+            {
+              "$ref": "#/definitions/Level"
+            }
+          ]
+        },
         "invalid-overload": {
           "title": "detects invalid `@overload` usages",
           "description": "## What it does\nChecks for various invalid `@overload` usages.\n\n## Why is this bad?\nThe `@overload` decorator is used to define functions and methods that accepts different\ncombinations of arguments and return different types based on the arguments passed. This is\nmainly beneficial for type checkers. But, if the `@overload` usage is invalid, the type\nchecker may not be able to provide correct type information.\n\n## Example\n\nDefining only one overload:\n\n```py\nfrom typing import overload\n\n@overload\ndef foo(x: int) -> int: ...\ndef foo(x: int | None) -> int | None:\n    return x\n```\n\nOr, not providing an implementation for the overloaded definition:\n\n```py\nfrom typing import overload\n\n@overload\ndef foo() -> None: ...\n@overload\ndef foo(x: int) -> int: ...\n```\n\n## References\n- [Python documentation: `@overload`](https://docs.python.org/3/library/typing.html#typing.overload)",