Docker: add health endpoints and healthcheck on management api, so that seed can be delayed #501
Description
Currently oftentimes the tenant seeds start, before the management API is up, which is used to seed the tenants.
This means the system does not have a valid tenant configuration in the DB and won't start in one go.
Add healthchecks to the management api, and set the dependency on the seeds so that they only start when the API is up.
Optionally add a dependency on the seeds to the connectors, so that they only start when the seed is finished.
This way we ensure that all is set up and can start in one go.