Add flexible servers to support managed post gresql flexible server

[Fred-sun]

SUMMARY

Add flexible servers to support managed post gresql flexible server, try to fixes #1167

ISSUE TYPE

• New Module Pull Request

COMPONENT NAME

azure_rm_postgresqlflexibleserver.py
azure_rm_postgresqlflexibleserver_info.py

ADDITIONAL INFORMATION

[timway]

I'm using this fork (with a minor tweak to allow version 14, PR to @Fred-sun on it). It seems serviceable so far. It needs the ability to configure the additional authentication types it seems yet. I may take a look at that in other commits as well if it becomes necessary.

[timway]

@xuzhang3 the other Postgres DB service will soon disallow provisioning instances. Let's start enabling folks to easily configure resources. I've created a number of flexible Postgres servers using this branch. I have a PR for @Fred-sun in the branch solely to bump the version of DB which appears to require a Python requirements bump.

Source: https://learn.microsoft.com/en-us/azure/postgresql/single-server/whats-happening-to-postgresql-single-server