Settings: threadpool and batch size

Add a new "tab" after Genesys API titled Advanced settings.

• Add a configuration setting for "Worker threads". Default value (also if not provided) should be 2.
• Add setting for "Batch size". Default value 100.

These settings should affect the threadPool and the number of records (batch) sent in one request to the server.

Settings need to be persisted in the workspace.json (and loaded). Ensure that if the JSON file does not have these properties the defaults are used.