Migrate all API calls to the camunda v2 api

[jonathanlukas]

As the Tasklist REST API is planned to be deprecated and removed, this client with allow for a smooth migration to the new Camunda REST API.

• Create abstraction
• deprecate current implementation
• each method needs an explanation on how to replace it
• each invocation will write a log that a deprecated method is used
• on bootstrapping, a deprecation warning will be logged as well