Support passing `--trigger` with `argo-workflows trigger`

[valayDave]

If a flow has the @trigger_on_finish decorator, you can locally test it being triggered by an already completed flow. We do this by passing a --trigger option to the run command like :python myflow.py --trigger FlowA/Runb run; This can be only done when using the local run and not when we are triggering with ArgoWorkflows.

This would be really useful when testing on remote; Desired behavior :

python myflow.py --trigger FlowA/Runb argo-workflows trigger