Implement From<BackendError> for Error

[andreeaflorescu]

Without this we need to add boiler plate code when creating custom filters:

....
    SeccompFilter::new(
        rules.into_iter().collect(),
        SeccompAction::Trap,
        SeccompAction::Allow,
        ARCH.try_into().unwrap(),
    )
    .map_err(Error::Backend)?
    .try_into()
    .map_err(Error::Backend)

If we implement From, then this could be simplified by just having:

    SeccompFilter::new(
        rules.into_iter().collect(),
        SeccompAction::Trap,
        SeccompAction::Allow,
        ARCH.try_into().unwrap(),
    )?
    .try_into()

[ramyak-mehra]

Do you want something like this? @andreeaflorescu

 impl From<BackendError> for Error {
    fn from(value: BackendError) -> Self {
        Self::Backend(value)
    }
}

[andreeaflorescu]

@ramyak-mehra yes. And the same can also be implemented for JsonFrontendError. Then, you should also check in the code where the errors are used because you can already do some simplifications.