Installer support for storage resource group and storage agent

[achimnol]

Things to do in the installers

To ease development and testing of frontend involving SFTP/filebrowser related features, we need to automate the initial configuration of them in development setups.

• Pull the sftp/filebrowser images and register them to the image metadata database. We could upload them to index.docker.io and let the installer perform the per-image rescan (Per-image sync from container registries (particularly, Docker Hub) #1621).

For single-node all-in-one setup

• Prerequisite: Exclude SYSTEM sessions from resource allocation while keeping per-container resource limits #1672
• Just share the default resource group and agent with other sessions to run DIRECT_ACCESS sessions.

For multi-node setup (with dedicated storage-proxy nodes)

• Prerequisite for flexible sharing of agent nodes: Running multiple agents on a single node #496
• Create a dedicated resource group and configure it as follows:
  • Update the storage volume access list (in the shared config) to include the default storage proxy volume.
  • Allow execution of DIRECT_ACCESS sessions only.
  • Allow all users to use this resource group.
• Create a dedicated agent configuration for agent(s) belonging to the above resource group.
  • Set the host port range to match with the firewall configuration.