[Hub Generated] Review request for Microsoft.DigitalTwins to add version stable/2020-12-01 (#10996)

* Adds base for updating Microsoft.DigitalTwins from version stable/2020-10-31 to version 2020-12-01

* Updates readme

* Updates API version in new specs and examples

* Update swagger spec

* Modify SDK build configs

* Fix example filename reference

* Rename example file

* Fix validation errors

* Updated examples

* Revert change to behavior of async op

* Modify discriminators

* Enable two discriminators

* Fix delete endpoint example

* Attempted fix with discriminator

* Added westus2, change discriminator enum type name

* Decouple allOf from properties

* Bugfixes

* Modify response to fix validation errors

* Fix examples

* Change private link type names to be smaller

* Fix validation errors in private links

* Fix validation error related to private links

* Reference private link example

* Add public network access

* Align with GA swagger

* Update private links / private endpoints

* Fix example to use actual response status code

* Remove unused example

* Unmark private endpoint connection to be an azure resource

* Add type and name to private endpoint connection resource

* Mark id as read-only

* Fix return types for endpoint connections

* Align return of DELETE

* Fix validation errors

* Fix version tag in python.md; remove body from DELETE endpoint connection DELETE responses

* Synchronize swagger with 2020-10-31 version

* Increase resource group name max length to 90 characters

* Make publicNetworkAccess nullable

* Add publicNetworkAccess flag to PATCH request

* Fixed typo

* Fix placing of example for endpoints

* Update operation ids

* Added suppression message