Feature: Attach Azure Key Vault Policy to an existing Key Vault

[danielkimuipath]

Hi Team,

I noticed that Key Vault Policy is part of Key Vault Resource. This design supports when KV is managed by ASO in the beginning but it does not support for addding Azure Key Vault policies for exisitng Key Vault that are managed externally.

Looking at Terraform's example, it has its own KV access policy separately - https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/key_vault_access_policy.

With this de-coupling from KV and KV policies, users can leave KV as it is and just manage the policy configuration within the KV independently.

Thanks!