Enable direct Harness Platform (Delegate-less) connectivity for the Azure Key Vault Connector using Service Principal or OIDC authentication.

Problem: The Azure Key Vault Connector currently requires a Delegate for connectivity. Because Harness Cloud build runners (e.g., Windows platform) cannot route through delegates, secret expressions (<+secrets.getValue(...)>) fail to resolve, returning raw ${ngSecretManager.obtain(...)} strings during execution.

Goal: Achieve feature parity with AWS Secrets Manager, GCP Secret Manager, and HashiCorp Vault by allowing direct Harness Platform secret resolution on Harness Cloud builds.