Check DKIM Authentication-Results (#3583)

Fix #3507

Note that this is not intended for a release at this point! We first have to test whether it runs stable enough. If we want to make a release while we are not confident enough in authres-checking, then we have to disable it.

BTW, most of the 3000 new lines are in `test_data/messages/dkimchecks...`, not the actual code

da3a4b94 adds the results to the Message info. It currently does this by adding them to `hop_info`. Maybe we should rename `hop_info` to `extra_info` or something; this has the disadvantage that we can't rename the sql column name though.

Follow-ups for this could be:
- In `update_authservid_candidates()`: Implement the rest of the algorithm @hpk42 and me thought about. What's missing is remembering how sure we are that these are the right authserv-ids. Esp., when receiving a message sent from another account at the same domain, we can be quite sure that the authserv-ids in there are the ones of our email server. This will make authres-checking work with buzon.uy, disroot.org, yandex.ru, mailo.com, and riseup.net.
- Think about how we present this to the user - e.g. currently the only change is that we don't accept key changes, which will mean that the small lock on the message is not shown.
- And it will mean that we can fully enable AEAP, after revisiting the security implications of this, and assuming everyone (esp. @link2xt who pointed out the problems in the first place) feels comfortable with it.

test-data/message/dkimchecks_strip.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+# This is a small script I used to strip all the unnecessary information from the realworldemails before committing them, to avoid blowing up the repo size.
+# Also, I deleted deltachattest@outlook.com/deltachat-dev@posteo.de.
+# Also, I anonymized them using
+#   for n in ...; do rename $n alice *; done
+#   for n in ...; do rename $n alice */*; done
+#   for n in ...; do find ./ -type f -exec sed -i -e "s/${n}/alice/g" {} \; ;done
+# (replace ... with the list of localparts in the email addresses)
+set -euxo pipefail
+cd dkimchecks-2022-09-28
+parent_dir=$PWD
+for d in *; do
+	cd $d
+	for file in *; do
+		if ! [[ -s $file ]]; then
+			rm $file || true
+		else
+			python3 $parent_dir/../dkimchecks_strip.py < $file > ${file}-new
+			mv -f ${file}-new $file
+		fi
+	done
+	cd $parent_dir
+done