Setup Helm storage code and manifests

Description

The most important thing is that the point no 1 needs to be done ASAP to unblock other subtasks.

[x] Bootstrap Go code for the helm storage backends
- Single entrypoint (directory in cmd)
- Based on flags, a different storage backend gRPC server is run
- Both servers (release + template) implement the same Storage Backend ProtoBuf interface (use already generated Go code)
- Modify pipelines to build a single Docker image
[x] Add dedicated Helm chart and Hub manifests to install Helm storage backends
- [x] Single Helm chart, one deployment, two containers and two separate services
- [x] Update pipelines for releasing Helm charts
- The implementation produces two TypeInstances for two storage backends (helm release backend + helm template backend) - define them
- Write instruction on PR how to install such storage backend. It will be later reused in documentation
- Base on secret storage backend, as this is pretty similar case (https://github.com/capactio/capact/issues/647)

See epic #650