Support native horizontal scalability and add an Helm chart

[aler9]

Describe the feature

Support native horizontal scalability and add an Helm chart.

[aler9]

TODO:

1. Allow multiple server replicas to share the same internal state, by using an external database (probably etcd)
2. Distribute paths among available replicas
3. If a replica receives a publish request that doesn't belong to it, proxy the request to the correspondent replica
4. If a replica receives a read request that doesn't belong to it, contact the replica that has the correspondent stream and proxy that stream
5. Create an Helm chart that allows users to instantiate and scale the server with no effort.

[pikachu937]

Support it