Support Application Settings and other options

[spmp]

Support for Application Settings - i.e environment variables, will greatly improve this tool and allow for more generic/multiple deployments from Azure Pipelines.

Many other web app settings would also be helpful on new resource creation, such as creation of MSI's, or attaching to user MSI's would be an advantage - as would security/endpoint/networking etc. options. These options are potentially not such a big deal as the web app can be created ahead of time with these settings.