support asyncio for workflow service

[yulin-li]

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For workflow service actions, such as list/submit workflows, it will be great if an asyncio version is provided in the SDK.

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provide an asyncio version of WorkflowsService based on e.g., aiohttp instead of request

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[flaviuvadan]

Hi @yulin-li, this is a great idea. Are you open to submit a PR? Hera uses this script https://github.com/argoproj-labs/hera/blob/main/scripts/service.py to generate the workflow service. We need an async_service.py with some templates adjusted and a Make recipe like this. The submit API of cron and workflow have to change as well to account for the async nature of the injected service as well