* Add matrix-registration-bot

This adds an install and uninstall task plus helpers. The bot is disabled by default.
This commit does not include documentation, yet. In short, the bot can be enabled by adding
matrix_bot_matrix_registration_bot_enabled: true
matrix_bot_matrix_registration_bot_matrix_user_password: "verysecret"
matrix_bot_matrix_registration_bot_matrix_admin_token: "supersecret"
to the host_vars

* Change bot username to bot.matrix-registration-bot following convention

* Address smaller remarks, fix local docker build

* Switch to an env file

* Add environment variables extension for additional config

* Add documentation for the matrix-registration-bot

* Add screenshot on how to obtain admin access token

* Use bot as admin to only have one access token (bot and admin api)

* Use cleaner setting of matrix_synapse_registration_requires_token

* Use config file for cleaner more secure usage

* Delete unneeded env

* Rename vars to make usage clear

* Fix typos/wording and add notice about logging out

* Convert configuration to use |to_json

* Reorder role includes

Nothing should be after `matrix-common-after`.

`matrix-bot-matrix-registration-bot` can probably be anywhere, but it makes sense to put it next to the other `matrix-bot-*` roles.

* Minor group_vars/matrix_servers touchups

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

Comments taken from https://github.com/matrix-org/matrix-appservice-slack/blob/develop/config/config.sample.yaml

We should probably reconcile our configuration with that one and include comments for other fields as well.

It is very confusing to debug why messages only go from Matrix to Slack
but not from Slack to Matrix. RTM should be enabled by default, as
that's the recommended way to make this work.

Added Storage Module to homeserver.yaml

WIP of #176

* matrix-backup-borg: added option for unencrypted repo access

* matrix-backup-borg: fixed requiring password for unencrypted repos; changed variable name

* matrix-backup-borg: add unknown_unencrypted_repo_access_is_ok to config.yaml.j2

* matrix-backup-borg: cleanup comments

* matrix-backup-borg: add documentation regarding unencrypted repos

* matrix-backup-borg: add readability and ease of use to code

* matrix-backup-borg: fix wording in defaults/main.yml comment

* matrix-backup-borg: add quotes to docs

* Indicate the variable to use

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

Increase the async timeout value defaults, as larger Matrix servers need more time to complete.