imap: do not treat messages without Message-ID as duplicates

Message-IDs are now retrieved only during fetching and saved into imap
table. dc_receive_imf_inner does not attempt to extract the Message-ID
anymore.

For messages without Message-ID the ID is now generated in
imap::fetch_new_messages rather than dc_receive_imf_inner,
so the same ID is used in the imap table (maintained by the imap
module) and msgs table (maintained by dc_receive_imf module).

Message-ID generation based on the Date, From and To field hashing has
been replaced with a simple dc_create_id() to avoid retrieving Date,
From, and To fields in the imap module, as it's hard to test that it
stays compatible between Delta Chat versions in this module. This
breaks jump-to-quote for quoted messages without Message-ID, which is
not critical.

Also prefetch X-Microsoft-Original-Message-ID, so retrieval of
duplicate messages with X-Microsoft-Original-Message-ID can be skipped
like it is done for messages with Message-ID header.

CHANGELOG.md

@@ -6,6 +6,9 @@
 - change semantics of `dc_get_webxdc_status_updates()` second parameter
   and remove update-id from `DC_EVENT_WEBXDC_STATUS_UPDATE` #3081
 
+### Fixes
+- do not delete messages without Message-IDs as duplicates #3095
+
 ### Changes
 - add more SMTP logging #3093
 - place common headers like `From:` before the large `Autocrypt:` header #3079