type-graphql validating inputs using yup instead of class-validator

formatYupError.ts

```

export const formatYupError = (err: ValidationError) => {
    const errors: Array<{ path: string; message: string }> = [];
    err.inner.forEach(e => {
        errors.push({
            path: e.path,
            message: e.message
        });
    });

    return errors;
};
```

ResolverWithMutation.ts

```
const validationSchema = yup.object().shape({
    email: yup
        .string()
        .min(3, emailNotLongEnough)
        .max(255)
        .email(invalidEmail)
        .required(),
    password: yup
        .string()
        .min(3, passwordNotLongEnough)
        .max(255)
        .required(),
    firstName: yup
        .string()
        .trim()
        .required()
        .min(2, "First name is too short"),
    lastName: yup
        .string()
        .trim()
        .required()
        .min(2, "Last name is too short")
});
// and inside the mutation's body
        try {
            await validationSchema.validate(
                {
                    email,
                    firstName,
                    lastName,
                    password
                },
                { abortEarly: false }
            );
        } catch (error) {
            throw new UserInputError(
                "Failed due to validation errors.",
                formatYupError(error)
            );
        }

```