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.

This also disables self-building on arm64, since it's no longer
necessary: https://github.com/matrix-org/matrix-appservice-slack/pull/656

Reference: https://ansible-lint.readthedocs.io/en/latest/default_rules/#var-naming

We don't really fix these, but just suppress them,
because they're like that intentionally.

We try to name variables in a way that is consistent with the
configuration key they control. If the upstream component uses
camelCase, we also need to include camelCase in the variable name.

Reference: https://ansible-lint.readthedocs.io/en/latest/default_rules/#var-spacing

Reference: https://ansible-lint.readthedocs.io/en/latest/default_rules/#git-latest

Our variable naming is not necessarily consistent across roles.
I've tried to follow the naming conventions of each individual role.
All new variables are suffixed with `_version`, but the prefix may be
somewhat different.

I am not using this bridge and haven't tested this but multiple people have said 1.5.0 isn't working and 1.8.0 works for them so it seems to make sense to update.

https://github.com/matrix-org/matrix-appservice-slack/issues/618#issuecomment-929849093

Signed-off-by: Ahmad Haghighi <haghighi@fedoraproject.org>

This is both for consistency with 93cc71cb69976c
and for making things more obvious.

We've had reports of the `:latest` tag not working anymore,
leading to an error as described here:
https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/341

This reverts commit 61e93744ec.

Reverting because of:
- https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/341
- https://github.com/matrix-org/matrix-appservice-slack/issues/347

NeDB is deprecated, so we should transition away from it in the future.
Still, most of the functionality should work on this new version.