[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.

Locate the Client V2 configuration entry points and compare them with the removed or renamed V1 parameters. Define the compatibility behavior for renamed and deprecated parameters, then write the configuration migration guide. Done means existing configurations can migrate through the friendly interface and the guide explains the required changes.

Written by the indexing model from the issue text.