Support for azurerm_postgresql_flexible_server

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Description

Anything in works to support postgres flexible server?

### New or Affected Resource(s)/Data Source(s)

azurerm_postgresql_flexible_server

### Potential Terraform Configuration

_No response_

### References

_No response_

The issue names azurerm_postgresql_flexible_server but does not identify files, tests, or a Terraform configuration. Start by reviewing the repository's existing resource patterns and determine the expected scope of support; done should mean the resource is supported with appropriate tests and documented behavior.

Written by the indexing model from the issue text.