MAR-192: Switch to using go-sendxmpp where possible for testing XMPP server role:

- The sendxmpp in Debian 12 Bookworm is quite broken at this point,
and go-sendxmpp is somewhat close in terms of interface etc.
- Fix a number of tests related to sending messages.

MAR-192: Added support for Debian 12 Bookworm to xmpp_server role:

- Some of the tests are still failing, namely the ones centered around
the sendxmpp tool (which seems completely broken at this point in
Debian 12 Bookworm)

MAR-192: Align IP ranges used for testing VMs in the xmpp_sever role:

- Use two consecutive ranges for Debian 11 Bullseye like in
mail_server.

MAR-189: Disable use of KVM paravirtualisation provider with Vagrant/VirtualBox:

- The VMs seem to randomly hang when the (KVM) clock source gets
initialised right after getting past the bootloader. Helps run the
tests in a way more reliable way.
- Should be removed if upgrading to latest kernel/VirtualBox versions
helps.

MAR-189: Added support for Debian 11 Bullseye to xmpp_server role:

- Roll-out LDAP client configuration since Bullseye does not come with
a stock one at /etc/ldap/ldap.conf that sets the trust anchor
correctly for validating LDAP server certificates.
- Drop the backports pinning in case of Bullseye (for now let's try to
keep the Buster and Bullseye at same versions for simplicity).
- Drop installation of Python apt bindings (no longer used).
- Tests for Buster and Bullseye need to be split-up a bit due to some
differences around backports etc.

MAR-189: Dropped deprecation-related tasks and tests for xmpp_server role:

- Migration from Prosody project repositories should have been done
already as part of the 7.0.1 release.
- Simplifies the code a bit.
- Drop leftover deprecated library plugin path.

MAR-181: Drop support for Debian 9 Stretch from the xmpp_server role:

- Switch to using IPs from VirtualBox default allowed host-only
network subnets.
- Drop Stretch-specific workarounds, code, and tests.

MAR-151: Added support for Debian 10 Buster to xmpp_server role:

- Updated role reference documentaiton.
- Updated role meta information.
- Updated tests.
- Enable lower-level TLS protocols (1.0/1.1) in global OpenSSL
configuration file on Buster in order to be able to test the
xmpp_server_tls_protocol parameter (otherwise Prosody completely
refuses to use them even if listed in its configuration).
- Move stretch-specific tests into its own file (for backported
lua-ldap library), and run them on Debian 9 Stretch machines only.

MAR-171: Make the xmpp_domains parameter mandatory:

- Updated release notes.
- Updated role reference documentation.
- Dropped the default value for parameter from the xmpp_server role.
- Updated tests.

MAR-150: Use fixtures for X.509 artefacts in the xmpp_server role:

- Removed the statically generated artefacts.
- Generate X.509 artefacts for tests using Gimmecert.
- Updated paths to point to generated artefacts.
- Introduced cleanup playbook for removing generated artefacts.

MAR-148: Disable Ansible's default of enforcing group names without dashes through Molecule configuration files:

The following links might be a useful read:

- https://github.com/ansible/ansible/issues/56930 (issues relaetd to
lack of docs, but many complaints and explanations within)
- https://groups.google.com/forum/#!topic/ansible-devel/bjAcM9ferIw

MAR-132: Added support to xmpp_server role for Debian 9 (Stretch):

- Updated tests to include Debian 9 in testing. Existing private keys
are reused where possible (since most of the naming is identical
between the machines with jessie/stretch).
- Updated invocation of sendxmpp in tests as workaround for
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=854210.
- Updated testing of imported keys to accomodate differences between
gpg/gpg2 (used by apt-key in Jessie/Stretch).

MAR-129: Updated xmpp_server role for Ansible 2.5.x and new Molecule:

- Include top-level lint configuration in test configuration.
- Fixed linting errors.
- Moved test playbook variables into group_vars and host_vars.
- Fixed deprecation warnings from Ansible.
- Updated how hosts are referenced within tests.

MAR-128: Upgraded tests for xmpp_server role:

- Switch to new Molecule configuration.
- Updated set-up playbook to use become: yes.
- Moved some preparatory steps outside of the main playbook (eases
idempotence tests).
- Updated tests to reference the yml inventory file.
- Updated tests to use new fixture (host instead of individual ones).
- Switched to extracting hostname instead of hard-coding it in a
couple of tests.
- Renamed hosts to include the Debian version.
- Updated names for some of the test data to cater to change in host
names.
- Switched to using more robust task for populating /etc/hosts.