Add Keyvault integration to Variable Groups. Add service connection creation

[devlace]

Type of PR

• Code changes

Purpose

• Creates a service connection per environment. Utilizes service principal already provided.
• Create a second Variable Group with KeyVault integration. Currently you cannot have a variable group with "mixed" variables (variables from keyvault and manually set variable), so a second variable group is needed for variables from Keyvault.

Does this introduce a breaking change? If yes, details on what can break

Author pre-publish checklist

• Added test to prove my fix is effective or new feature works
• No PII in logs
• Made corresponding changes to the documentation

Validation steps

• Deploy sample as per instruction. Check if service connections are created. Check if variable groups are created with KeyVault integration

Issues Closed or Referenced

• Closes Update variable groups to incorporate key-vault integration #1002