CodeGen from PR 14313 in Azure/azure-rest-api-specs

[Azure Cognitive Search][Resource Manager]: Add Swagger API for 2021-04-01-Preview API version (#14313)

* Add 2021-04-01-Preview as an exact copy of 2020-08-01-Preview

* Add new properties to swagger

* User Assigned Identity support
* Semantic search
* New auth options
* Enforcement of CMK
* Data exfiltration disablement
* Fix-up of S360 violations

* Add examples

* Fix R2026 - AvoidAnonymousTypes for UserAssignedIdentities

* Update readme files

* Make public network access extensible enum

* Case change byPass -> bypass

* Make some enum values extensible

Co-authored-by: Arvind Krishnaa Jagannathan <[email protected]>

Author: SDKAuto