Merge #3033

3033: Enable snowball on FTS r=mergify[bot] a=nextgens

## What type of PR?

enhancement

## What does this PR do?

Enable [snowball](http://snowball.tartarus.org/algorithms/english/stemmer.html), a filter that will significantly cut down the size of FTS indexes.

It looks like the packages for aarch64 haven't been built yet... but this works on x64_86.
Don't unblock as long as  https://dl-cdn.alpinelinux.org/alpine/edge/testing/aarch64/dovecot-fts-flatcurve-0.3.4-r3.apk is 404

### Related issue(s)
- close #2977 

## Prerequisites
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [ ] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/workflow.html#changelog) entry file.


Co-authored-by: Florent Daigniere <nextgens@freenetproject.org>

webmails/roundcube/config/config.inc.php

@@ -18,6 +18,11 @@ $config['session_lifetime'] = {{ (((PERMANENT_SESSION_LIFETIME | default(10800))
 $config['request_path'] = '{{ WEB_WEBMAIL or "none" }}';
 $config['trusted_host_patterns'] = [ {{ HOSTNAMES.split(",") | map("tojson") | join(',') }}];
 
+{% if (FULL_TEXT_SEARCH or '').lower() not in ['off', 'false', '0'] %}
+$config['search_mods'] = ['*' => ['subject'=>1, 'from'=>1, 'to'=>1, 'cc'=>1, 'bcc'=>1, 'replyto'=>1, 'followupto'=>1, 'body'=>1]];
+$config['search_scope'] = 'sub';
+{% endif %}
+
 // Mail servers
 $config['imap_host'] = 'tls://{{ FRONT_ADDRESS or "front" }}:10143';
 $config['imap_conn_options'] = array(

webmails/snappymail/defaults/default.json

@@ -12,7 +12,10 @@
             "SNI_enabled": true,
             "disable_compression": true,
             "security_level": 1
-        }
+        },
+	{% if (FULL_TEXT_SEARCH or '').lower() not in ['off', 'false', '0'] %}
+        "fast_simple_search": "false"
+	{% endif %}
     },
     "SMTP": {
         "host": "{{ FRONT_ADDRESS }}",