Add --tpu-topology flag for specifying custom topology types

[Obliviour]

Fixes / Features

• Supports tpu-topology flag for specifying custom topologys for TPUs

Testing / Documentation

Added a check to make sure the format of topologies fits with the argument expected and the command fails if the format is unexpected.

• [ y ] Tests pass
• [ y ] Appropriate changes to documentation are included in the PR

[Obliviour]

The workload creation needs to know the topology as well so CURRENTLY the user needs to set the same topology for workload create and cluster create. This only adds the flag to cluster create.

In this case, users would have to manage the topology.