[clang-tidy] support expect no diagnosis test (#91293)

When someone wants to declare a test case without any diagnosis.
check-clang-tidy will failed with error message

```
CHECK-FIXES, CHECK-MESSAGES or CHECK-NOTES not found in the input
```

This PR want to check there are no diagnosis from clang-tidy when
CHECK-FIXES, CHECK-MESSAGES or CHECK-NOTES are not found.

It also changes the extension of a test case. `hxx` is not a valid test
case extension and won't be tested.

---------

Co-authored-by: Danny Mösch <danny.moesch@icloud.com>