Better validation errors

Is your feature request related to a problem? Please describe.
At the moment, validation errors are emitted with this code:

    for v in self.validators:
            if self.null and value is None:
                continue
            try:
                if isinstance(value, Enum):
                    v(value.value)
                else:
                    v(value)
            except ValidationError as exc:
                raise ValidationError(f"{self.model_field_name}: {exc}")

I usually want to get the value of the field that caused the error so that I can inform the frontend of the problematic field.

The problem is that, to get the value of the field that cause the error: self.model_field_name, I need to use a regular expression on the string.

Describe the solution you'd like
I would like to have an error class that has specific field and msg instance attributes. The msg attribute would not contain the field value.

Describe alternatives you've considered
Using a regex to isolate the field / msg.

Additional context
None.

Start in tortoise/fields/base.py at the validator loop linked in the issue, then search for ValidationError consumers and existing validation tests. The work is done when validation errors expose separate field and msg attributes, with the requested message behavior covered by tests.