LanguageService does not retain active session with server

[cheenamalhotra]

Azdata Language service is opening a new connection every time it runs a query, and doesn't retain an active connection session with server. Connection activity tracked with profiler:

Discussed offline with @alanrenmsft - it does seem like a bug that should be addressed.

Expected:
Active Connection session is maintained with server similar to azdata-Query connection, that only gets terminated when Query tab is closed.

Impact:
This bug has a large impact on Azure connections, as creating a new connection is very time consuming and expensive. Keeping an active connection from client will prevent recurring connection attempts. Server will terminate the connection when there's no activity after long time, but it will be resiliently reconnected when client tries to execute a query.

P.S. Please make sure connection resiliency is tested on Unix platforms by disconnecting WiFi and reconnecting it. Connection to target server should be re-established without user noticing it.