Console backend should parse console-config.yaml for TopologyMode

Upon console backend startup, console-config.yaml, which is generated by the console-operator, should be parsed in order to get the `ClusterInfo.TopologyMode`. That value should be set as a new `ClusterTopologyMode` server flag.

Acceptance criteria:

• Parse console-config.yaml for `ClusterInfo.TopologyMode` value and set it as `ClusterTopologyMode` server flag.

Depends on: CONSOLE-3070