Add Azure policy pack - Tagging Helpers for Cost_Center. Closes #865

[vkumbha]

Tags on Storage Account: cost-Centre: Z4192

Once the Policy Pack is attached, Turbot identifies

tagsToCreate:
  Cost_Center: Z4192
tagsToUpdate: {}
tagsToDelete:
  cost-Centre: Z4192
updates: true

Turbot has Enforced the Cost_Center Tag Transform

Tags on Storage Account after enforcement: