message: add AzPowerShellSetup and its TypeProperties
diff: "componentName"
  ]
  },
  + "AzPowerShellSetup": {
  + "description": "The express custom setup of installing Azure PowerShell.",
  + "type": "object",
  + "allOf": [
  + {
  + "$ref": "#/definitions/CustomSetupBase"
  + }
  + ],
  + "properties": {
  + "typeProperties": {
  + "description": "Install Azure PowerShell type properties.",
  + "x-ms-client-flatten": true,
  + "$ref": "#/definitions/AzPowerShellSetupTypeProperties"
  + }
  + },
  + "required": [
  + "typeProperties"
  + ]
  + },
  + "AzPowerShellSetupTypeProperties": {
  + "description": "Installation of Azure PowerShell type properties.",
  + "type": "object",
  + "properties": {
  + "version": {
  + "description": "The required version of Azure PowerShell to install.",
  + "type": "string"
  + }
  + },
  + "required": [
  + "version"
  + ]
  + },
  "EntityReference": {
  "description": "The entity reference.",
  "type": "object",
  