Rethink IntoResponse

[geofmureithi]

From #57 by @sandhose

Yes, I understood that! I'm talking about the IntoResponse trait being generic over the whole result instead of the output, despite using the JobError in all of its implementation

I'm basically suggesting changing this:

pub trait IntoResponse {
    type Result;
    fn into_response(self) -> Self::Result;
}

to

pub trait IntoResponse {
    type Output;
    fn into_response(self) -> Result<Self::Output, JobError>;
}

This way you keep the same flexibility of returning any kind of result, but it simplifies the generic bounds in some places

[geofmureithi]

I am open to seeing how this would look for something like:
async fn job(email: Email, ctx: JobContext) -> Result<(), anyhow::Error>