Output VMSS dynamic name within AKS

**What happened**:

Currently VMSS of AKS is dynamically named and not outputted within AKS.

**What you expected to happen**:

We are using Infrastructure as Code to provision AKS cluster and enable VM insights for those VMSS. Therefore, we need to read the VMSS name outputted from AKS cluster.

**How to reproduce it (as minimally and precisely as possible)**:

Provision AKS via IaC and no VMSS name in AKS outputs.

**Anything else we need to know?**:
None

**Environment**:
- Kubernetes version (use `kubectl version`): 1.20.9 [AKS version]