CodeGen from PR 24087 in Azure/azure-rest-api-specs

[PostgreSQL] New api version 2023-03-01-preview - Migrations API property update, enum values update. Network property changes ported. (#24087)

* Port network property fix from api version 2022-12-01 to 2023-03-01-preview

* FIx request and response for Migrations api for the new version 2023-03-01-preview

* Fix prettier errors

* Add more example for Migrations api

* Fix model validation and prettier errors

* Update default tag for postgresql flexible servers in readme.md to assist in auto-generation of SDK

* Update the duplicate entity name for Serverku used in Migrations.json to avoid errors

* Revert "Update the duplicate entity name for Serverku used in Migrations.json to avoid errors"

This reverts commit 01712362ac9c0327acfa8be3f49a8d5bd6417b66.

* Update duplicate entity name ServerSku in Capabilities.json to avoid duplicate entity name errors.

Author: SDKAuto