Add support for ignoring errors.AsType error return value checks

[weisdd]

In Go 1.26, there was a new pattern for error type comparison introduced (docs):

if _, err := os.Open("non-existing"); err != nil {
	if pathError, ok := errors.AsType[*fs.PathError](err); ok {
		fmt.Println("Failed at path:", pathError.Path)
	} else {
		fmt.Println(err)
	}
}

Sometimes, we care only about error type, so there is no need to have an extra variable:

if _, ok := errors.AsType[*folders.DeleteFolderNotFound](err); !ok {
	return err
}

In this case, errcheck will emit the "Error return value is not checked" error.

Adding "nolint" comments everywhere (for golangci-lint) is a bit burdensome, and it appears that exclude-functions doesn't respect errors.AsType / errors.AsType(err error). So, I guess, some code modifications in the linter itself are needed.