Replace traefik with nginx/certbot + curlable bash script

[spwoodcock]

Fixes #838

Includes

1. Replaced vars:

URL_SCHEME
API_URL
FRONTEND_MAIN_URL

# Also no longer required (determined from FMTM_DOMAIN)
OSM_LOGIN_REDIRECT_URI

# Replaced with much simpler / clearer:
FMTM_DOMAIN

2. Added an nginx proxy to route all services:

During development we can now access:

• fmtm.localhost (frontend)
• api.fmtm.localhost (backend)
• odk.fmtm.localhost (odk central, although internal to docker containers in the stack this will just be called proxy. From the backend we can give pass ODK_CENTRAL_URL=https://proxy.)
• s3.fmtm.localhost (the Minio S3 buckets)

In production, these will be mapped to domain names:
fmtm.hotosm.org
api.fmtm.hotosm.org
etc

See #920 for more info

3. Certbot to automatically renew certs for the provided domains (to replace Traefik).

Extra

Also fixes: #928, adding regular database backups.
Also fixes #899, adding a curlable bash script (easier deployment).