Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3133

Regression since 4ed522e8fe

This should resolve [#2296](https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2296) by fixing the noted issue.

This also paves the way for in the future working on D4A mode but that would require a rework to how these variables are done.

Most addons live in the same network by default (matrix-addons) right now,
so this network would have usually been created by some other addon.

Howevre, if this is the only addon someone uses, it may have remained
uncreated causing a problem.

Related to: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3100

I believe `specialized-workers` is a better name than `room-workers`,
because when enabled, 4 different types of specialized workers are
created:

- Room workers
- Sync workers
- Client readers
- Federation readers

Only one of these is called room-workers.

In the future, more specialized workers may be added, making the
`room-workers` preset name an even poorer choice.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3100

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3100

Until now, the validation check would only get tripped up
if generic workers are used, combined with at least one EACH
other type of specialized workers.

This means that someone doing this:

```
matrix_synapse_workers_preset: one-of-each
matrix_synapse_workers_client_reader_workers_count: 5
```

.. would not have triggered this safety check.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3100

Hookshot wants a trailing slash for this route.

If we let Hookshot redirect, it goes to `/widgetapi/v1/static/`,
instead of `/hookshot/widgetapi/v1/static/`, so we take this matter into our
own hands.

Public URLs are like: `/hookshot/widgetapi/v1/static/`
.. which get translated to requests for: `/widgetapi/v1/static/`

Previously, we were stripping the whole `/hookshot/widgetapi` prefix,
which is wrong.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3114

Most of these files were defining a service, usually toward the end.
These lines have been moved upward.

Some components (mautrix-signal, mautrix-gmessages, etc.) were defining
a service conditionally (only if metrics are exposed, etc). This was
causing issues like these in the Traefik logs:

> level=error msg="service \"matrix-mautrix-twitter\" error: port is missing" providerName=docker container=matrix-mautrix-twitter-..

This changes the behavior of
`matrix_playbook_migration_matrix_nginx_proxy_uninstallation_enabled`
and is against what we initially described in the changelog entry,
but I've discovered some problems when the `matrix-nginx-proxy` service
and container remain running. They need to go.

After some checking, it seems like there's `/_synapse/client/oidc`,
but no such thing as `/_synapse/oidc`.

I'm not sure why we've been reverse-proxying these paths for so long
(even in as far back as the `matrix-nginx-proxy` days), but it's time we
put a stop to it.

The OIDC docs have been simplified. There's no need to ask people to
expose the useless `/_synapse/oidc` endpoint. OIDC requires
`/_synapse/client/oidc` and `/_synapse/client` is exposed by default
already.

10 seconds is a better default for slower (or overloaded) servers

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3102

Issues and Pull Requests were not migrated to the new
organization/repository, so `matrix-org/synapse/pull` and
`matrix-org/synapse/issues` references were kept as-is.

`matrix-org/synapse-s3-storage-provider` references were also kept,
as that module still continues living under the `matrix-org` organization.

This patch mainly aims to change documentation-related things, not actual
usage in full yet. For polish that, another more comprehensive patch is coming later.