Fix 20210301preview bugs (#15146)

* Add Identity to createWorkpace example

* change for getTransitivePEUsages

* update

* prettier code

* add another new endpoint

* address comments

* change for getTransitivePEUsages

* update

* prettier code

* add another new endpoint

* address comments

* revert change on transitivePE and notebookKeys

* revert change on transitivePE and notebookKeys

* add new stable version 2021-01-01

* add ListNotebookAccessToken

* add primaryUserAssignedIdentity

* fix missing properties and apis

* fix one more missing property

* 202 status for start and stop CI

* make resync keys long runnin operation in version Jan2021

* resync keys 204

* update resync keys example

* Dont throw 204 for resync

* update resync keys

* Formatting

* revert Jan2021changes and add new version

* start apr2021 version for azure ml rp

* undo remove new line in jan2021

* use systemData definition in common

* removed old files

* fix small swagger bugs

* run prettier

* remove reference to sku

* update readme

* minimum agentCount should be 0

* add createdOn and ModifiedOn to compute properties

* add LoadBalancerType to aks compute

* add isNotebookInstanceCompute to virtualMachine

* add leafDomainLabel to SslConfiguration

* add overwriteExistingDomain to SslConfiguration

* add synapseSpark as supported compute-type

* update patch compute response to 202

* remove location from example responses

* Revert "remove location from example responses"

This reverts commit 048bf25.

* MachineLearningCompute_Update should have a 200 response

* sys data to use local def due to naming conflicts.

* Fix enum casing

* Fix operationId PR comment.

* Change opId in apr version

* remove 20210401 for easy review

* only change api version

* merge changes for 20210401 version

* Add x-ms-discriminator-value for Synapse spark

* camelcase loadbalancer properties

* add createdOn and Modified on to examples

* address AvoidAnonymousTypes error for SynapseSpark

* Minor fixes + new property

* Remove subscription state.

* fix bug

Co-authored-by: Vinay Rajmal Soni <vison@microsoft.com>
Co-authored-by: Suba <sukaruna@microsoft.com>
Co-authored-by: jopet@microsoft.com <jopet@microsoft.com>
Co-authored-by: Josh Peterson <15050193+joshanator@users.noreply.github.com>
Co-authored-by: Suba <sk.suba1@gmail.com>

Author: 5 people

specification/machinelearningservices/resource-manager/Microsoft.MachineLearningServices/preview/2021-03-01-preview/machineLearningServices.json

@@ -4379,13 +4379,13 @@
         },
         "notebookPreparationError": {
           "$ref": "#/definitions/NotebookPreparationError",
-          "description": "The error that occurs when preparing notebook."
+          "description": "The error that occurs when preparing notebook.",
+          "x-nullable": true
         }
       }
     },
     "NotebookPreparationError": {
       "type": "object",
-      "x-nullable": true,
       "properties": {
         "errorMessage": {
           "type": "string"