Update to the existing Azure DevTest Lab swagger definition. (#1067)
Update to the existing Azure DevTest Lab swagger definition. (#1067)

* Update to the existing Azure DevTest Lab swagger definition.

The changes included in this pull request are already in our production service.  We support back-compat for these changes in our RP implementation.
This pull request contains the following changes to our API:
1. Introduce new properties for virtual machine creation (Claimable, Expiration, Shared IP address, and Bulk-creation)
2. Introduce new resource models
  a. Target Cost - https://azure.microsoft.com/en-us/updates/azure-devtest-labs-cost-threshold-notification-and-custom-cost-tracking-time-range/
  b. Notification (i.e. webhook integration) - https://azure.microsoft.com/en-us/updates/azure-devtest-labs-auto-shutdown-notification/
  c. Environments (i.e. ARM templates) - https://azure.microsoft.com/en-us/blog/announcing-azure-devtest-labs-support-for-creating-environment-with-arm-templates/
  d. Lab resource usage
  e. Managed disk

* Added required property attributes

* Convert to 4 space indent to be consistent with previously submitted model

* Update based on feedback

* remove schema tag

* Add root level attributes back to createEnvironment

AppPlatPerf/azure-rest-api-specs,AzureAutomationTeam/azure-rest-api-specs,brjohnstmsft/azure-rest-api-specs,deathly809/azure-rest-api-specs,amarzavery/azure-rest-api-specs,AuxMon/azure-rest-api-specs,yugangw-msft/azure-rest-api-specs,sethmanheim/azure-rest-api-specs,solankisamir/azure-rest-api-specs,vladrai/azure-rest-api-specs,Nking92/azure-rest-api-specs,JasonYang-MSFT/azure-rest-api-specs,olydis/azure-rest-api-specs,Nking92/azure-rest-api-specs,bganapa/azure-rest-api-specs,johanste/azure-rest-api-specs,amarzavery/azure-rest-api-specs,yaakoviyun/azure-rest-api-specs,nathannfan/azure-rest-api-specs,vladrai/azure-rest-api-specs,AuxMon/azure-rest-api-specs,hyonholee/azure-rest-api-specs,johanste/azure-rest-api-specs,naveedaz/azure-rest-api-specs,begoldsm/azure-rest-api-specs,AppPlatPerf/azure-rest-api-specs,hovsepm/azure-rest-api-specs,jcyang75/azure-rest-api-specs,kiwidev/azure-rest-api-specs,DeepakRajendranMsft/azure-rest-api-specs,shimedh/azure-rest-api-specs,felixwa/azure-rest-api-specs,naveedaz/azure-rest-api-specs,dashimi16/azure-rest-api-specs,henry416/azure-rest-api-specs,solankisamir/azure-rest-api-specs,sudhansu88/azure-rest-api-specs,kirthik/azure-rest-api-specs,AsrOneSdk/azure-rest-api-specs,dmakwana/azure-rest-api-specs,henry416/azure-rest-api-specs,mihymel/azure-rest-api-specs,hyonholee/azure-rest-api-specs,akshaysngupta/azure-rest-api-specs,Nking92/azure-rest-api-specs,brjohnstmsft/azure-rest-api-specs,jobatzil/azure-rest-api-specs,AsrOneSdk/azure-rest-api-specs,dihan0604/azure-rest-api-specs,kiwidev/azure-rest-api-specs,yaakoviyun/azure-rest-api-specs,deathly809/azure-rest-api-specs,yugangw-msft/azure-rest-api-specs,amolr/azure-rest-api-specs,jonpayne/azure-rest-api-specs,hovsepm/azure-rest-api-specs,vishrutshah/azure-rest-api-specs,d3r3kk/azure-rest-api-specs