accept incoming DMARC and TLS reports with reporting addresses containing catchall separator(s)

Such as "-" when addresses are dmarc-reports@ and tls-reports@.

Existing configuration files can have these combinations. We don't allow them
to be created through the webadmin interface, as this is a likely source of
confusion about how addresses will be matched. We already didn't allow regular
addresses containing catchall separators.

testdata/smtp/dmarcreport/domains.conf

@@ -1,11 +1,19 @@
 Domains:
 	mox.example:
 		DMARC:
-			Account: mjl
-			Localpart: mjl
+			Account: dmarc
+			# Localpart contains a catchall separator
+			Localpart: dmarc-reports
 			Mailbox: DMARC
+		LocalpartCatchallSeparators:
+			- +
+			- -
 Accounts:
 	mjl:
 		Domain: mox.example
 		Destinations:
 			mjl@mox.example: nil
+	dmarc:
+		Domain: mox.example
+		Destinations:
+			dmarc@mox.example: nil