Developer dashboard should read the version from the node and not a static value in the config map

As a first-MVP approach to showing the cluster version in the developer dashboard, we updated the cluster terraform module to get the version from the cluster and write it to the config map where the developer dashboard will then read it.

This presents 2 problems:

1. The logic to get the cluster version is hokey and adds a dependency on the IBM Cloud cli. Removing this would simplify the module
2. The logic is currently only available in the IBM Cloud version of the module
3. The cluster version is stored in the config map and never updated. The version of the cluster can change through upgrades so this information is out of sync
4. We are storing and potentially maintaining a value that is readily available in the cluster already

The nodes all have a label (on IBM Cloud anyway) with the version - `ibm-cloud.kubernetes.io/worker-version`. A simple query in the UI backend logic could read that value from the node directly.