[feature request] fail on specific errors only

Hi there,

### tl;dr
At the moment `--fail-early` throws me out of the `--parallel` download 
with every error 404, even though this error often isn't that fatal. 
Adding a range of error codes to the `--fail` family could help here:

```
--fail 400-403,405-
--fail-early 400-403,405-
--fail-on-error 400-403,405-
```

Where `400-403` means `400, 401, 402, 403` and `405-` means `405, 406, 
407, ...`.
Alternatively: `--fail-early !404` for ignoring 404 (which might lead to 
problems in some shells).

### Detailed explaination
The parameters `--fail` and `--fail-early` might be to strict for some 
situations.  This has to do with the fact that 401 or 403 is often an 
actual reason to cancel a request, while error 404, for example, could 
still contain important information (for example an error message).

It would therefore be great if you could choose which error codes lead 
to a cancellation.

I'm aware that you could automate the whole thing using `--write-out` 
and shell scripting, but then you would not be able to benefit from the 
excellent `--parallel` function.

Best regards,
Tobias
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