When a CA fails to issue a certificate after finalisation Certbot
currently prints the following unhelpful message:
```
An unexpected error occurred:
acme.errors.IssuanceError
```
This PR makes Certbot print the ACME error object from the order, as
such
```
An unexpected error occurred:
CAA error :: Invalid CAA: CAA prohibits issuance
```
## Pull Request Checklist
- [ ] The Certbot team has recently expressed interest in reviewing a PR
for this. If not, this PR may be closed due our limited resources and
need to prioritize how we spend them.
- [x] If the change being made is to a [distributed
component](https://certbot.eff.org/docs/contributing.html#code-components-and-layout),
edit the `master` section of `certbot/CHANGELOG.md` to include a
description of the change being made.
- [x] Add or update any documentation as needed to support the changes
in this PR.
- [x] Include your name in `AUTHORS.md` if you like.
This is, to my knowledge, an entirely inconsequential PR to add support for entirely novel challenge types.
Presently in the [`challb_to_achall` function](https://github.com/certbot/certbot/blob/399b932a869403b142fb0271aec510614085d6ed/certbot/certbot/_internal/auth_handler.py#L367) if the challenge type is not of a type known to certbot an error is thrown. This check is mostly pointless as an authenticator would not request a challenge unknown to it. This check does however forbid any plugins from supporting entirely novel challenges not of the key authorisation form.
* support unknown ACME challenge types
* add to changelog
* update tests
---------
Co-authored-by: Brad Warren <bmw@eff.org>
