Update Container Apps resources test template to new resource provider

**Description of the issue**

During the month of March 2022, all Azure Container Apps resources will be gradually migrated from the Microsoft.Web namespace to the Microsoft.App namespace.

https://github.com/microsoft/azure-container-apps/issues/109

`Resources.ContainerApp.json` should be adjusted accordingly.

Start by locating Resources.ContainerApp.json and inspect how the Azure Container Apps resource provider is represented in the template. Update the provider namespace from Microsoft.Web to Microsoft.App, then run the repository's relevant resource template tests and confirm they pass.

Written by the indexing model from the issue text.