Checkpoint: returning kedifa-caucase-url

XXX: TODO

https://github.com/eclipse-theia/theia/blob/v1.18.0/CHANGELOG.md#v1180---9302021

See merge request nexedi/slapos!1061

Adapt all promise sections to changes in plugin promise recipe.

As Debian Bullseye has been released, set it as first option.

As Debian Buster 10.11 update has been released, upgrade it.

The real predicate to find the master partition is rejected slave publisher
configuration.

After upgrade to OpensSSH 8.8p1 the simple ssh-rsa keys are not accepted
anymore.

Also move component/stunnel to unstable

powerdns needs a pkgconfig file from lua to compile

nis module is linking against system libraries

This is almost the smae as for python3 (see e1cee1fc)

Without this fix, selecting a completion with the keyboard is not really
possible.

This reverts commit fb3ee44e
partially, for dream.

Add tests for Wendelin Learning Track tutorial
https://wendelin.nexedi.com/wendelin-Learning.Track

Add port-listening promises for all sources found in fluentd configuration file

There can be a short delay until the partially uploaded file is actually
removed, so wait a little bit before checking for its absence.

Our old subversion does not seem to support the expiration of letsencrypt root certificate, as we can see in [tests](
https://erp5js.nexedi.net/#/test_result_module/20210930-70CDB278/143): 

```
ClientError: ("Unable to connect to a repository at URL 'https://svn.erp5.org/repos/public/erp5/trunk/bt5/test_web'\nServer SSL certificate verification failed: certificate has expired", [("Unable to connect to a repository at URL 'https://svn.erp5.org/repos/public/erp5/trunk/bt5/test_web'", 230001), ('Server SSL certificate verification failed: certificate has expired', 230001)])
```

This is also what we observe when using svn command from ERP5 software release:

```
~/srv/slapos/shared/subversion/26833ca5dbfd6944dc2e584d0761dc89/bin/svn info https://svn.erp5.org/repos/public/erp5/trunk/bt5/test_web
Error validating server certificate for 'https://svn.erp5.org:443':
 - The certificate has expired.
Certificate information:
 - Hostname: svn.erp5.org
 - Valid: from Sep 26 05:47:35 2021 GMT until Dec 25 05:47:34 2021 GMT
 - Issuer: Let's Encrypt, US
 - Fingerprint: 01:98:FF:1B:68:A1:55:59:35:EE:1C:57:8A:6E:5A:22:1F:3E:B2:86
(R)eject, accept (t)emporarily or accept (p)ermanently? ^Csvn: E200015: Unable to connect to a repository at URL 'https://svn.erp5.org/repos/public/erp5/trunk/bt5/test_web'
```

Updating subversion and linking it with openssl 1.1 seem to solve the issue.

See merge request nexedi/slapos!1053

This has been superseeded by switch-softwaretype recipe.