Adds support for: https://src.miscworks.net/fair/matrix-appservice-kakaotalk

This is pretty similar to
https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1977
which just appeared, but has mostly been done independently.

I've taken some inspiration and did some fixups based on that PR.
Thanks to https://github.com/hnarjis for taking the time to contribute!

Notable differences between this branch compared to that PR:

- better naming and documentation around the "configuration" variables
- no unnecessary (5 sec.) intentional delay when starting `matrix-appservice-kakaotalk-node.service`
- stores configuration in `config/`, not in `data/`
- passes configuration as read-only and starts the bridge with (`--no-update`) to ensure no changes are made to it
- starts containers more securely - with `matrix:matrix` user:group (not `root`) and
  reduced capabilities (`--cap-drop=ALL`)
- uses `tcp` for communication between the "node" and the appservice (simpler than sharing unix sockets)
- `registration.yaml` which is closer to the one generated by `matrix-appservice-kakaotalk` (no `de.sorunome.msc2409.push_ephemeral` stuff, etc.)
- `registration.yaml` which is more customizable (customizable bot username and prefix for puppets - see `matrix_appservice_kakaotalk_appservice_bot_username` and `matrix_appservice_kakaotalk_user_prefix`)
- less fragile and more extensible bridge permissions configuration via `matrix_appservice_kakaotalk_bridge_permissions`. Doing `{% if matrix_admin %}` in the bridge configuration sometimes causes syntax problems (I hit some myself) and is not ideal. Other bridges should be redone as well.
- configurable command prefix for the bridge, instead of hardcoding `!kt` (see `matrix_appservice_kakaotalk_command_prefix`)
- logging that is more consistent with the rest of the playbook (console / journald only, no logging to files), as well as configurable log level (via `matrix_appservice_kakaotalk_logging_level`)
- somewhat more detailed documentation (`docs/configuring-playbook-bridge-appservice-kakaotalk.md`)
- removed some dead code (data relocation tasks from `tasks/setup_install.yml`, as well as likely unnecessary SQLite -> Postgres migration)

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1894

* Make interface hidden behind proxy by default

* Remove expose option and replace with http_bind_port

Reasoning: This is a similar binary trigger but allows to bin not on all interfaces

* Clarify maubot admin purpose

* Remove unnecessary edif

* Extend docs to prevent common misconceptions

* Make http_bind_port singular, do not allow multiple values

* Make optional again

Make use of `example.com` more consistent (replace `DOMAIN`) and simplify Caddy 2 config. Remove Caddy 1 config since Caddy 1 is long past EOL.

Synapse no longer describes the stats as anonymized since the `server_name` is included.
https://github.com/matrix-org/synapse/pull/13321

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1931

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1931

This does 2 things:

- it fixes the syntax for `matrix_id`. Starting strings with `@` is
  invalid YAML, so such strings need to be wrapped in single or double
  quotes
- it makes use of the `matrix_domain` variable instead of hardcoding the
  domain name. This should be more and mistake-proof (typos or people
  mistaking their domain - matrix. vs base domain)

* Implement MSC 1929 Homeserver Admin Contact
Fixes #1612

For details to the proposed (not accepted yet) MSC, see:
https://github.com/matrix-org/matrix-spec-proposals/blob/hs/proposal-admin-contact-1/proposals/1929-admin-contact.md

* Implement feedback from PR #1931

* Implement feedback from PR #1931

* Fix mixed indentation

project doesn't exist on github anymore

Unrelated to the original branch I added the matrix-registration bot as it was missing in the readme

* 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>

Adding the defaults in addition to template, switching YOUR_DOMAIN to {{ matrix_domain }}, and giving example of the two combined, as the playbook gives a warning about things being defined twice, so only using the last one in the vars.yml

Fixing code block formatting

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1899

Copy/Pasting from docs/configuring-playbook-bridge-mautrix-facebook.md but with the relevant variable names changed to add turning on encryption and a puppet admin.

Adding a bit on how to bind the synapse ports if the webserver isn't in the same docker network, or on a different machine.

Logging in from the IP address is no longer always enough, but 2FA seems to work eventually

servers

Fixup for #1877.

Based on mautrix-whatsapp, as that's what the bridge software is based on.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1772

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1864

Related to https://github.com/zeratax/matrix-registration/issues/93

This is a poor way to do things though. It may break again in the future.
matrix-registration is a poorly maintained project and should likely be removed from the playbook.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1792

fix Hookshot instructions link