Microsoft.Automation/schedules: Ambiguous type for "interval" parameter

The ARM API specs for `Microsoft.Automation/schedules` do not specify a type for the `interval` property. This causes the Azure documentation (and other tooling, like the VSCode extension) to assume an `object` type.

However, looking at the [quickstart templates](https://docs.microsoft.com/en-us/azure/templates/microsoft.automation/automationaccounts/schedules#quickstart-templates) using this type of resource, it appears that this property is actually a string. For example, see [azuredeploy.json](https://github.com/Azure/azure-quickstart-templates/blob/master/oms-azure-resource-usage-solution/azuredeploy.json) for the [Azure Resource Usage Solution](https://github.com/Azure/azure-quickstart-templates/tree/master/oms-azure-resource-usage-solution) (lines [1228](https://github.com/Azure/azure-quickstart-templates/blob/master/oms-azure-resource-usage-solution/azuredeploy.json#L1228) and [483](https://github.com/Azure/azure-quickstart-templates/blob/master/oms-azure-resource-usage-solution/azuredeploy.json#L483)).

This appears to affect all API versions (though I was testing with 2015-10-31).

Inspect the Microsoft.Automation/schedules API specifications, beginning with version 2015-10-31, and compare the interval property with the quickstart template azuredeploy.json at the referenced lines. Check the other API versions mentioned by the issue; done means interval is represented as a string rather than an object wherever this resource is specified.

Written by the indexing model from the issue text.