Give function app resource group scoped contributor role

[tevoinea]

Summary of the Pull Request

What is this about?

In #1693, we removed the Onefuzz Deployment custom role since we can't rely on it being in any arbitrary azure tenant. In order to give the Functions App permissions to create the auto scale resources, we're giving it Contributor access to the resource group. Unfortunately, we can't scope down the permissions further since there's no other built-in roles that provide Microsoft.Insights/autoscalesettings/Write permission.

Docs used for resource scoped role assignment: https://docs.microsoft.com/en-us/azure/role-based-access-control/role-assignments-template#resource-group-scope-without-parameters

PR Checklist

• Closes Use tenant agnostic role for providing Microsoft.Insights/autoscalesettings/Write permission #1697
• Tests added/passed
• Requires documentation to be updated
• I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

Info on Pull Request

What does this include?

• ARM template change to add the Contributor role to the Function App
• Contributor role id: b24988ac-6180-42a0-ab88-20f7382dd24c

Validation Steps Performed

How does someone test & validate?

• Ran dev deployment and validated the Function App now has Contributor role