* one var to control encryption across all bridges

* move var to matrix-base

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.

* Creating generic mautrix bridge doc

Not a huge fan of how it turned out at all, not sure how to make it better.

* Rename configuring-playbook-bridge-mautrix-Generic.md to configuring-playbook-bridges.md

* accepting suggested edits after rename mess

* Adding log level configuration

* Update docs/configuring-playbook-bridges.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Rename configuring-playbook-bridges.md to configuring-playbook-mautrix-bridges.md

Co-authored-by: ThellraAK <ThellraAK@pop-os.localdomain>
Co-authored-by: Slavi Pantaleev <slavi@devture.com>