New resource azurerm_iotcentral_application_network_rule_set

[myc2h6o]

Similar to azurerm_servicebus_namespace_network_rule_set_resource, IoT Central Application creates a default Network Rule Set, and it could not be removed even when set to nil/empty explicitly, so adding it with an extracted resource azurerm_iotcentral_application_network_rule_set.

Other changes within this:

• when parent resource azurerm_iotcentral_application performs an update to the property with UpdateThenPoll, it wipes out the Network Rule Set, so using CreateOrUpdateThenPoll with modifying the existing resource.
• azurerm_iotcentral_application.sku supports Update, but was missing in the Update function, adding it there. (The update test didn't catch it because the sku in the updated test config is same as the default value.)
• Supported value ST0 of sku is missing in the doc of azurerm_iotcentral_application, adding it there
• azurerm_iotcentral_application.template cannot be updated as described here, so changing it to ForceNew. (The update api ignores the new value and doesn't throw an error)
• Adding few tests for azurerm_iotcentral_application to cover the Update scenarios of its properties

[myc2h6o]

I put the update of the azurerm_iotcentral_application here together with this change because azurerm_iotcentral_application_network_rule_set breaks without the change the Update function in azurerm_iotcentral_application. I've put these fixes alone in the separate pr #18590 as well. If it's not ok to mix things together here, please feel free to leave this one alone and review the other one first.

[myc2h6o]

Test result

[katbyte]

LGTM 🚡

[github-actions]

This functionality has been released in v3.26.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

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[github-actions]

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