This container needs a writable $HOME, and will fail at startup if
there isn't one.

Provide one by pointing HOME to a path under the mounted /data
directory.

Related to https://github.com/matrix-org/synapse/commit/3479599387164aca2613e88d169719

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2392

Co-Authored-By: Slavi Pantaleev <slavi@devture.com>

* Allow the mautrix whatsapp relaybot to be enable with a variable

This allows a user to enable the relaybot by setting a variable in
`vars.yml` in the same way that the mautrix signal relaybot is
configured.

* Correct default values for mautrix whatsapp relaybot variables

* Add documentation for using the relaybot with mautrix whatsapp

* Adjust variable names to better reflect what they do

* Set default variables properly and use to_json in template

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2369

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2363

Fixes the following issue when trying to use the !pm <phone number> command: https://gitlab.com/signald/signald/-/issues/345

Conduit update 0.5.0 fixed the issue, so this is no longer needed.