lacme(8): for --config=, --socket=, --config-certs= (and ‘socket’/
‘config-certs’/‘challenge-directory’ configuration options *before*
privilege drop; and for the [accountd] section ‘command’/‘config’
configuration options *after* privilege drop).

lacme-accountd(1): for --config=, --socket= and --privkey= (and
‘socket’/‘privkey’ configuration options).

This also changes the default configuration file location.  lacme(8) and
lacme-accountd(1) now respectively use /etc/lacme/lacme.conf resp.
/etc/lacme/lacme-accountd.conf when running as root, and
$XDG_CONFIG_HOME/lacme/lacme.conf resp. $XDG_CONFIG_HOME/lacme/lacme-accountd.conf
when running as a normal user.  There is no fallback to /etc anymore.

To correctly extract the parent directory of the socket path.  The
previous returned an empty string when the socket path didn't contain
‘/’.

This allows us to fully validate provided X.509 chains using that
self-contained bundle, regardless of which CAs is marqued as trusted
under /etc/ssl/certs.

Also, remove cross-signed intermediate CAs from the bundle as they're
useless in a self-contained bundle.

Also, remove decomissioned intermediate CAs Authority X3 and X4 from the
bundle.

This change bumps the minimum OpenSSL version to 1.1.0 (for
verify(1ssl)'s ‘-trusted’ and ‘-show_chain’ options).

For DEP-14 compliance.

This removes the dependency on Types::Serialiser.

We were blocking on https://github.com/letsencrypt/boulder/issues/3530 .