Support for private AKS clusters

See #89.

This adds support for a new variable, private_cluster_enabled, which enables the use of private clusters.

Fix for kube_dashboard profile

This fixes an issue where unnecessary updates were being attempted.

Fix Sensitive Output

Fixes: #80

Update default cluster/uai names

Addresses: #68

• change default cluster name (remove "aks-" prepend)
• change default uai name to "aks--control-plane"kkk

Backwards compatibility can be maintained by using the setting the following attributes to existing values:

• cluster_name
• user_assigned_identity_name

Fix Issue with empty API access parameter

Api restriction fix (#77)

* fix input restriction bug

* fix bug with null ip restriction

Co-authored-by: Tim Miller <tim.miller@risk.lexisnexis.com>

Fix Typo

Api typo (#76)

* fix input restriction bug

* fix typo

Co-authored-by: Tim Miller <tim.miller@risk.lexisnexis.com>

Additional Networking/Policy Support

• Network Policy Support #71
• Azure Policy Add-on Support #72
• API server authorized IP Ranges support #75

Network Changes

• configuring NSG rules is no longer a feature (subnets with pre-configured egress must be used)
• using input subnets requires a corresponding route_table_id

UAI Fix

• Updated azurerm provider (2.57.0) fixes the inability to modify a cluster when using User-Assigned Identity

AzureCNI/NetworK Mode Fix

This fixes an issue when trying to set network mode attribute. In certain circumstances, it has caused issues when a cluster was originally built with the attribute unset. Anything other than "transparent" has been deprecated and AKS uses "transparent" by default, so there is no advantage to setting it. As such, it has been removed from the module.