add automated test for quickstart

with tls with acme (with pebble, a small acme server for testing), and with
pregenerated keys/certs.

the two mox instances are configured on their own domain. we launch a separate
test container that connects to the first, submits a message for delivery to
the second. we check if the message is delivered with an imap connection and
the idle command.

testdata/quickstart/moxacmepebble.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+set -x # print commands
+set -e # exit on failed command
+
+apk add unbound curl
+
+(rm -r /tmp/mox 2>/dev/null || exit 0) # clean slate
+mkdir /tmp/mox
+cd /tmp/mox
+mox quickstart moxtest1@mox1.example "$MOX_UID" > output.txt
+
+sed -i -e '/- 172.28.1.10/d' -e 's/- 0.0.0.0/- 172.28.1.10/' -e '/- ::/d' -e 's/letsencrypt:/pebble:/g' -e 's/: letsencrypt/: pebble/g' -e 's,DirectoryURL: https://acme-v02.api.letsencrypt.org/directory,DirectoryURL: https://acmepebble.example:14000/dir,' config/mox.conf
+cat <<EOF >>config/mox.conf
+
+TLS:
+	CA:
+		CertFiles:
+                        # So certificates from moxmail2 are trusted, and pebble's certificate is trusted.
+			- /quickstart/tls/ca.pem
+EOF
+
+(cat /quickstart/example.zone; sed -n '/^;/,/IN CAA/p' output.txt) >/quickstart/example-quickstart.zone
+unbound-control -s 172.28.1.30 reload # reload unbound with zone file changes
+
+CURL_CA_BUNDLE=/quickstart/tls/ca.pem curl -o /quickstart/tmp-pebble-ca.pem https://acmepebble.example:15000/roots/0
+
+mox serve &
+while true; do
+	if test -e data/ctl; then
+		echo -n accountpass1234 | mox setaccountpassword moxtest1@mox1.example
+		break
+	fi
+	sleep 0.1
+done
+wait