Add various polish to Conduwuit

https://github.com/Virkkunen and I have been working on the same feature
simultaneously.

This patch adds my additional independent work on top of his changes.

Notable changes here compared to Virkkunen's original work:

- renaming config-related variables (`matrix_conduwuit_*` ->
  `matrix_conduwuit_config_*`). This is consistent with other roles (and
  better), but deviates from how the Conduit role was implemented.

- using a full configuration sample from https://conduwuit.puppyirl.gay/configuration.html
  instead of using the old Conduit config file template

- introducing configurability for more Conduwuit config settings, to support easy registration, etc.

- removing configuration settings that Conduwuit does not support
  anymore (e.g. `max_concurrent_requests`)

- cross-linking docs pages for Conduit and Conduwuit

- a Conduwuit docs page which is much improved compared to the old
  Conduit one

- REAMDE updates

roles/custom/matrix-conduwuit/vars/main.yml

@@ -1,3 +1,4 @@
 ---
+
 matrix_conduwuit_client_api_url_endpoint_public: "{{ 'https' if matrix_playbook_ssl_enabled else 'http' }}://{{ matrix_conduwuit_hostname }}/_matrix/client/versions"
 matrix_conduwuit_federation_api_url_endpoint_public: "{{ 'https' if matrix_playbook_ssl_enabled else 'http' }}://{{ matrix_conduwuit_hostname }}:{{ matrix_federation_public_port }}/_matrix/federation/v1/version"