local.json is automatically generated and can change due to updates,
to prevent breaking changes, only append the necssary config
using a custom entrypoint.
This upgrades onlyoffice to v7, adds a seperate postgresdb + rabbitmq and adds env variables for the forcesave option.
Co-authored-by: Philipp Rothmann <philipprothmann@posteo.de>
Reviewed-on: #5
