Generate from latest api spec, bump version to 7.2.0-preview (#12004)

* Generate from latest api spec, bump version to 7.2.0-preview

* Update versions in AssemblyInfo

eng/mgmt/mgmtmetadata/cognitiveservices_resource-manager.txt

@@ -1,14 +1,14 @@
-Installing AutoRest version: latest
+Installing AutoRest version: v2
 AutoRest installed successfully.
 Commencing code generation
 Generating CSharp code
 Executing AutoRest command
-cmd.exe /c autorest.cmd https://github.com/Azure/azure-rest-api-specs/blob/master/specification/cognitiveservices/resource-manager/readme.md --csharp --version=latest --reflect-api-versions --csharp-sdks-folder=D:\Github\azure-sdk-for-net\sdk
-2020-03-10 19:43:16 UTC
+cmd.exe /c autorest.cmd https://github.com/Azure/azure-rest-api-specs/blob/master/specification/cognitiveservices/resource-manager/readme.md --csharp --version=v2 --reflect-api-versions --csharp-sdks-folder=C:\Repos\azure-sdk-for-net\sdk
+2020-05-11 21:35:19 UTC
 Azure-rest-api-specs repository information
 GitHub fork: Azure
 Branch:      master
-Commit:      f0e5030929b9bbeacc13249c309b5b14cbbdedef
+Commit:      3e8fb815e2e4f149fbfcdaab64efc4d45dcc0690
 AutoRest information
-Requested version: latest
-Bootstrapper version:    autorest@3.0.6187
+Requested version: v2
+Bootstrapper version:    autorest@2.0.4413