Multiple sessions per connection

[zaza81]

Some systems (See CNC )in order to scale horizontally need to achieve the following features.

• Pull of connection per DB Instance
• each connection can have a pull of sessions.

Acceptance criteria

• change the SDK to accept multiple sessions
• the limit of sessions per connection is defined on immudb server

As an example of managing multiple connections on SDK, we should take the following example. @tomekkolo can you add your SDK example?

[tomekkolo]

Here is simple PoC of multiple sessions client: https://github.com/codenotary/immudb/commit/d48b6e24f35b8acc59740cb3e81c7d6ce93bdea7