Feature Request: Enable "system assigned" Identity for LogicApp via ARM template

[Create logic app](https://github.com/Azure/azure-quickstart-templates/blob/master/101-logic-app-create/azuredeploy.json)

I need to create a logic app and enable "system assigned" Identity for it.
I'm looking for a way to enable this setting via ARM template at the time of deployment.

Thanks,
Sourabh

Start with 101-logic-app-create/azuredeploy.json and review how the Logic App resource is configured. Determine how the ARM template can enable a system-assigned identity, then validate that the template deploys a Logic App with that setting enabled.

Written by the indexing model from the issue text.