This commit adds copyright attirbutions in SPDX format to files for matrix-bot-go-neb, following the REUSE's specification.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

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 is a mistake made in 10b5350370.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2540

Completely untested.