Disable result_unwrap_used / option_unwrap_used in tests

[llogiq]

If clippy is used as a dependency, the lints can pick up test code. Since that code does not need to have full-blown error handling, unwrap is ok.

To solve this, we can use get_parent to walk up the parent chain and check all items for #[test] annotations.

[link2xt]

This will not work properly if test module contains helper functions that do unwrap() and #[test] function calls this helper function rather than unwrap(). Such lints should be disabled for the whole test module.

[llogiq]

We now have an is_in_test function in clippy_utils that checks both function and module path.

[smoelius]

Should this be configurable? I.e., is the change in behavior a concern?