[client-v2] Implement adoption of old configuration parameters.

Client V2 has removed (deprecated) some V1 configuration parameters. That was done to simplify and remove redundant configuration, and some parameters were renamed for better readability. However, users may struggle with migration because they have to re-implement client configuration in their applications. Client V2 should have a friendly interface:
- It should accept renamed parameters.
- Deprecated parameters may be present for some time.
- Configuration migration guide should be written.