[Task] Refactor tags into new package to align with azurerm provider

[pbolduc]

The terraform-provider-azurerm provider has moved the tag schema, validation and other functions into separate package back in Aug 2019. Having the terraform-provider-azurerm provider diverge makes it more difficult to create new resources on Azure Stack (ie #50) that are derived from the Azure Cloud. If the model in the Azure Cloud has stabilized, I propose starting migrating to similar packages in Azure Stack.

This issue is specifically for tags. Separate issues can be created for other kinds.

The complete list :

terraform-provider-azurestack file	terraform-provider-azurerm package
azurestack/locks.go	azurerm/internal/locks
azurestack/tags.go	azurerm/internal/tags
others?

Once the new package is committed, a sweep of the source code can be completed to update references.

[pbolduc]

Going to close this issue/PR for now. It seems there is the intention to add engineering effort on this teams to accelerate the development.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 [email protected]. Thanks!