[Feature][ACNS] Add support to enable the Hubble UI through the Azure CLI

[tiesmaster]

Is your feature request related to a problem? Please describe.
Although, the Hubble UI can be deployed separately, and is described in the documentation for Advanced Container Networking Services. The problem is that the deployment of the Hubble UI is very tightly coupled to the deployment of the Hubble Relay, which is controlled by AKS, and this introduces additional maintenance toil on consumers of ACNS.

One thing that we saw, is that the version of the Hubble UI needs to match exactly the version of the manifest from the documentation. It uses v0.12 of the Hubble UI. We've tested with the latest version v0.13, and that broke the Hubble UI (I can provide detailed logs, if needed). Since, hubble-relay is managed by the AKS team, it makes sense to have AKS also manage the Hubble UI deployment.

Describe the solution you'd like
A flag in the aks-preview Azure CLI extension to enable the Hubble UI when enabling Container Network Observability.

Describe alternatives you've considered
Installing the Hubble UI via the provided manifest as described above, which works but has the mentioned downsides also described above.

Additional context
This issue is related, but is much broader, as it is also about situations like "BYOCNI", the Hubble Exporter. This request is solely about being able to enable the Hubble UI when AKS is already managing the hubble-relay.