Update dns suffix/fully qualified name based on the cloud environment or from the created object

[jananivMS]

Closes #672

What this PR does / why we need it:

• The dns suffix for SQL database differs based on the cloud environment. This is used in the fully qualified server name in Azure SQL server secret, in the listener endpoints in the Failovergroup secret and in the sql user secret. These are updated to use the SQLdatabaseDNSSuffix defined in the Cloud environment
• The postgreSQL fully qualified server name needs to be retrieved from the created server object so it is accurate (differs in different cloud environments)

Special notes for your reviewer:
Test the following operators in Public and China clouds and make sure the fields in the secrets only have environment appropriate strings (.com or .net for Public cloud, .cn or .chinacloudapi for ChinaCloud)

• Azure SQL server
• Azure Failovergroup
• Azure SQL user
• Postgresql server

How does this PR make you feel:

If applicable:

• this PR contains documentation
• this PR contains tests

[buhongw7583c]

Due to the quota limitation on China cloud, could use break points to check the dns suffix of secret for SQL server and SQL failover group (no need to create them successfully), which turned out to be correct: *.database.chinacloudapi.cn.

But could not verify on SQL user or psql server without creating them.

[jananivMS]

@buhongw7583c I was able to validate Azure SQL server, Azure SQL user and PostgreSQL server on China Cloud. Can you please review the code and approve if it looks good to you?