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-181: Refactor the Prosody package version checks:

- Move the Prosody package version check into default set of tests.

MAR-181: Use Debian-provided Prosody package instead of project repository:

- Upstream repository has a tendency to drop support for older Debian
releases, and to completely wipe old version repositories.
- It should be way less hassle to simply start using the
Debian-provided packages instead.
- Introduces deprecation tests to check if the role will also clean-up
the non-Debian packages.

MAR-174: Enable Message Carbons (XEP-0280) and Message Archive Management (XEP-0313) via xmpp_server role:

- Updated release notes.
- Updated role reference documentation.
- Enable the two modules via Prosody configuration file, and set the
archive expiration configuration option for Prosody.
- Updated tests.

MAR-173: Switch to using Prosody 0.11 as default version in the xmpp_server role:

- Updated default value for the Prosody package parameters.
- Configure the backports repository on the server, and pin the
lua-ldap package to be installed from the backports
repository (needed for Lua 5.2 support).
- Drop the explicit installation of lua-sec library - it is already
installed as pre-requisite for the Prosody package.

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-164: Harden the c2s TLS configuration for the XMPP server role:

- Updated the xmpp_server role.
- Added (optional) xmpp_server_tls_protocol and
xmpp_server_tls_ciphers parameters for specifying the desired
TLS protocol version and ciphers for the c2s connections.
- Updated XMPP server configuration to introduce separate TLS
configuration for the s2s and c2s (legacy included) connections.
- Drop support for Prosody 0.9 since it is not possible to have
separate TLS configuration for c2s and s2s connections.
- Updated role reference documentation.

MAR-162: Make the xmpp_tls_certificate and xmpp_tls_key parameters mandatory in xmpp_server role:

- Dropped the defaults from wsgi_server role.
- Updated group variables in role tests.
- Changed the key/certificate file extensions to be more descriptive.
- Updated role reference documentation.
- Updated usage instructions to include the mandatory parameters.
- Deduplicated tests for the TLS files.

MAR-149: Switch to using File.content_string instead of File.content in tests for all roles:

- The .content variant returns contents as bytes, while the
content_string returns a string (which is what is wanted in
practically all cases).

MAR-138: Switch to using Prosody stable branch nightlies:

- Introduced additional parameter for specifying name of Prosody
package to install.
- Updated tests.

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.