Feature: Functionality to add/remove/update connectors without explicitly having to stop the pipeline.

### Feature description

Any modification to a connector requires the pipeline to be stopped and started after changes have been completed.
This introduces more state handling to the user as they have to do multiple operation to accomplish a single mutation.

E.g. adding a new connector to a running pipeline requires:
1. Stop pipeline
2. Add connector
3. Start pipeline

And this could be replaced with a single operation and delegating the pipeline state change
to conduit.

For more context please see https://github.com/ConduitIO/conduit/discussions/189