Always send direct messages to the user’s bare JID

This has the following advantages:

- Works while all resources are offline (persistent channels)
- Helps with combating duplicate messages when sent to different
  resources, resources going offline, carbon-copying etc. etc.

As a side effect, this also makes the MUC PMs not be MUC PMs and
always be emitted from the server-wide JID of the sending user.

Fixes #3313.
13 jobs for feature/to-bare-jid in 9 minutes and 12 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #25150
docker
build:alpine

00:04:12

passed #25149
docker
build:debian

00:04:18

passed #25148
docker
build:fedora

00:04:12

passed #25151
docker
build:no_botan

00:04:11

passed #25155
docker
build:no_db

00:04:11

passed #25156
docker
build:no_db_botan

00:04:11

passed #25153
docker
build:no_libidn

00:04:11

passed #25154
docker
build:no_sqlite3

00:04:11

passed #25152
docker
build:no_udns

00:04:11

 
  Test
passed #25160
docker
test:alpine

00:02:25

passed #25157
docker
test:debian

00:02:23

passed #25158
docker
test:fedora

00:04:58

passed #25159
docker
test:no_udns

00:02:11