r/resource_group: feature flag for prevent_deletion_if_contains_resources

[magodo]

This PR introduces a new feature block resource_group with a toggle delete_nested_items_during_deletion (same name as the template_deployment), which by default is false that only allows users to delete a resource group when it is empty.

NOTE This PR makes the toggle to be false by default, which is a breaking change comparing to the current provider behavior. So we'd either merge it for v3.0, or make it true by default.
(Using the ThreePointOh internal toggle might cause miss changes for (e.g.) document when we switching to v3.0 in this case?)

Fixes #1608

Test Result

Run a basic test for VM to ensure when this feature is disabled, the listing by resource group API returns empty list when all the resources inside the resource group are deleted prior to Terraform trying to delete this resource group.

💤 TF_ACC=1 go test -timeout=3h -v ./azurerm/internal/services/compute -run='TestAccLinuxVirtualMachine_authPassword'
=== RUN   TestAccLinuxVirtualMachine_authPassword
=== PAUSE TestAccLinuxVirtualMachine_authPassword
=== RUN   TestAccLinuxVirtualMachine_authPasswordAndSSH
=== PAUSE TestAccLinuxVirtualMachine_authPasswordAndSSH
=== CONT  TestAccLinuxVirtualMachine_authPassword
=== CONT  TestAccLinuxVirtualMachine_authPasswordAndSSH
--- PASS: TestAccLinuxVirtualMachine_authPasswordAndSSH (252.47s)
--- PASS: TestAccLinuxVirtualMachine_authPassword (279.01s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm/internal/services/compute     279.052s

[tombuildsstuff]

Rebased on top of main

[tombuildsstuff]

hi @magodo

Thanks for this PR - apologies for the delayed review here, I've wanted to spend some time digging into this to ensure the behaviour's what we expect.

I've taken a look through and left some comments inline - since I've rebased this PR anyway I'm going to push a commit to fix those and ask @jackofallops to take another look through, but I think that should enable us to ship this.

Thanks!

[jackofallops]

LGTM 👍

[github-actions]

This functionality has been released in v2.72.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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